US – Union Symposia

US2 – Post-Covid Geosciences

The World Meteorological Organization (WMO) Research Board has set up an interdisciplinary and international Task Team to respond to the challenge of providing timely decision support and relevant knowledge on Meteorological and Air Quality (MAQ) factors affecting the SARS-CoV-2/COVID-19 pandemic. The Task Team aims to provide decision makers and the public with a rapid summary of the state of knowledge regarding potential MAQ influences on SARS-CoV-2/COVID-19; to offer general technical guidance for researchers and service providers who wish to consider MAQ data in their analyses, estimates, predictions and projections of COVID-19 risks. The work of the task  motivated both by the global relevance of the subject and by the staggering number of papers and pre-prints currently available, which emphasizes the need for careful review and communication of the state of the science. This first  report presents a summary of key findings of the review to date, as informed by peer reviewed literature.


A key finding is that the underlying mechanisms that drive seasonality of respiratory viral infections are not yet well understood. To date, COVID-19 transmission dynamics appear to have been controlled primarily by government interventions rather than meteorological factors. Respiratory viral infections frequently exhibit some form of seasonality, particularly in temperate climates and some evidence from laboratory studies of SARS-CoV-2, suggests that the virus survives longer under cold, dry, and low ultraviolet radiation conditions. There is also evidence that chronic and short-term exposure to air pollution exacerbates symptoms and increases mortality rates for some respiratory diseases and this is consistent with early studies of COVID-19 mortality rates. However, there is no direct, peer reviewed evidence of pollution impacts on the transmission of SARS-CoV-2 at this time. Process-based modeling studies anticipate that COVID-19 transmission may become seasonal over time, suggesting Meteorology and Air Quality (MAQ) factors may support monitoring and forecasting of COVID-19 in the coming months and years.


Additional research quantifying links between MAQ factors and COVID-19 is needed.

How to cite: Omumbo, J.: First Report of the WMO COVID-19 Task Team on Meteorological and Air Quality (MAQ) factors affecting the COVID-19 pandemic., EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-16347,, 2021.

EGU21-7905 | Presentations | US2

Epidemics and Human Mobility

Theo Geisel

The severity of infectious diseases and epidemics increases drastically, when pathogens start being transmitted between humans, as thereby they can dispose of human traffic networks for their spreading. This can transform an epidemic into a worldwide threatening pandemic, as the current COVID-19 crisis has shown. Traffic networks exist on multiple scales and the spreading of pathogens exhibits superdiffusive properties. This talk will emphasize and analyze the key role of human mobility for the modeling, forecast, and control of epidemic spreading. A major problem is posed by the limited availability of statistical data on human mobility. Various proxies are now utilized since we suggested dollar bills as proxies for human moblity.  Recent work on endemic diseases in populations open to migration will be discussed. 

How to cite: Geisel, T.: Epidemics and Human Mobility, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-7905,, 2021.

EGU21-7976 | Presentations | US2

Geoclimatic, demographic and socio-economic determinants of the Covid-19 prevalence

Jacques Demongeot, Kayode Oshinubi, Mustapha Rachdi, and Herve Seligmann

We propose a panorama of already known Covid-19 determinants and some other new factors depending on three families of variables, i.e., geoclimatic (like temperature or elevation), demographic (like population density or median age) and socio-economic (like Gini' index or health expenditures as percentage of GDP) parameters. The influence of these determinants differs between the first and the second wave and we give some explanation of this phenomenon, which takes into account various geographical, political and biological characteristics of the populations concerned by the Covid-19 outbreak.









What do you want to do ?
New mail

How to cite: Demongeot, J., Oshinubi, K., Rachdi, M., and Seligmann, H.: Geoclimatic, demographic and socio-economic determinants of the Covid-19 prevalence, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-7976,, 2021.

EGU21-9286 * | Presentations | US2 | Highlight

Tracking COVID-19 in Real-time: Challenges Faced and Lessons Learned

Lauren Gardner

In response to the COVID-19 public health emergency, we developed an , first released publicly on January 22, 2020, hosted by the Center for Systems Science and Engineering (CSSE) at Johns Hopkins University. The dashboard visualizes and tracks the number of reported confirmed cases, deaths and recoveries for all countries affected by COVID-19. Further, all the data collected and displayed on the dashboard is made freely available in a GitHub repository, along with the live feature layers of the dashboard. The motivation behind the development of the dashboard was to provide researchers, public health authorities and the general public with a user-friendly tool to track the outbreak situation as it unfolds, critically, with access to the data underlying it. The demand for such a service became evident in the first weeks the dashboard was online, and by the end of February we were receiving over one billion requests for the dashboard feature layers every day, which since increased to between three and 4.5 billion requests every day. The dashboard has been featured on most major national and international media outlets (NYT, Washington Post, CNN, NPR, etc), and is either directly embedded in their websites, or used as the data source for in-house mapping efforts. Further, members of the public health community, including local and national governmental organizations, emergency response teams, public health agencies, and infectious disease researchers around the world rely on the dashboard and its data for informing and planning COVID-19 response. In this talk I will give a brief overview of the evolution of the dashboard, discuss some of the challenges we faced along the way, and suggest some methods by which disease tracking could be done better in the future.

How to cite: Gardner, L.: Tracking COVID-19 in Real-time: Challenges Faced and Lessons Learned, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-9286,, 2021.

US4 – Towards evolvable physics-based plants and landscape processes in terrestrial biosphere models

EGU21-16530 | Presentations | US4 | Highlight

State-of-the-art in 4D measurements

Eetu Puttonen, Juha Hyyppä, Paula Litkey, Mariana Batista Campos, Heikki Hyyti, Yunsheng Wang, Antero Kukko, Harri Kaartinen, Leena Matikainen, Mikko Vastaranta, Samuli Junttila, Matti Vaaja, and Petteri Alho

Light detection and ranging (lidar) has become an essential tool in mapping and change detection in different environments over the last 20 years. Laser scanners capture point clouds to create accurate digital snapshots of their surroundings. These snapshots tell about the structural information in the scene and can be readily returned to again and again to detect and measure any changes with multi-temporal measurements. However, multitemporal measurements cannot typically resolve the change events nor can they resolve more high frequency dynamics that happen on daily or weekly basis in the scene. Also, lidar systems operate still mainly with single wavelength limiting their usability in classification tasks. First multi- and hyperspectral systems have been already demonstrated, but have yet to break through in wider usage. Finnish Geospatial Research Institute (FGI) has been prototyping with different 3D measurement systems for the last 10 years to improve multitemporal mapping (4D) solutions. The prototypes include both hyperspectral and long-term multi- and hypertemporal lidar systems, and their combinations in static and mobile configurations. FGI started early on to experiment with hyperspectral laser sources (2007) and successfully demonstrated the first hyperspectral laser scanner prototype in 2012. The system was later used in detecting intraday vegetation dynamics in 2015. Multitemporal multispectral ALS measurements have been conducted since 2015 in Evo and in Espoolahti. The first long-term multitemporal studies with FGI mapping platforms were started with ALS to monitor changes in forests (1998) and built environment (2001) and with mobile laser scanning in studying the erosion of an arctic river basin (2008) annually.  Multitemporal ALS studies with vegetation started in 1998 in Kalkkinen and in 2007 in Evo followed with bi-temporal studies with TLS. Test Site Evo has been acquired with ALS. In 2020, Evo test site was granted Academy of Finland Research Infrastructure (RI) status. The RI will collect a 30-year-long time series with annual measurements using various laser scanning sensors for investigating single tree growth processes, forest dynamics, understanding cyclic forest while having variation at diurnal and annual scales and forest monitoring technologies. Vegetation dynamics monitoring was extended in 2020, when FGI started set up a permanent TLS measurement station in a boreal forest. The TLS station accurately detects structural changes of hundreds of tree crowns around it. The experiment aims to detect the changes of phenological state the trees and further link them with the environmental parameter variation. 4D measurements have successfully demonstrated their potential in extending the information available from laser scanning systems. To improve the usage of these novel information, automated pre-filtering of the vast data amounts already at sensor level will be imperative. Different lidar platforms can operate throughout the spatial scale from millimeter precision all way to national coverage. Thus, development of new scalable lidar RIs open new possibilities to complement already existing infrastructures.

How to cite: Puttonen, E., Hyyppä, J., Litkey, P., Batista Campos, M., Hyyti, H., Wang, Y., Kukko, A., Kaartinen, H., Matikainen, L., Vastaranta, M., Junttila, S., Vaaja, M., and Alho, P.: State-of-the-art in 4D measurements, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-16530,, 2021.

EGU21-16528 | Presentations | US4

New deep-learning based approaches for forest modeling beyond landscape scale

Werner Rammer and Rupert Seidl

In times of rapid global change, the ability to faithfully predict the development of vegetation on larger scales is of key relevance to society. However, ecosystem models that incorporate enough process understanding for being applicable under future and non-analog conditions are often restricted to finer spatial scales due to data and computational constraints. Recent breakthroughs in machine learning, particularly in the field of deep learning, allow bridging this scale mismatch by providing new means for analyzing data, e.g., in remote sensing, but also new modelling approaches. We here present a novel approach for Scaling Vegetation Dynamics (SVD) which uses a deep neural network for predicting large-scale vegetation development. In a first step, the network learns its representation of vegetation dynamics as a function of current vegetation state and environmental drivers from process-based models and empirical data. The trained model is then used within of a dynamic simulation on large spatial scales. In this contribution we introduce the conceptual approach of SVD and show results for example applications in Europe and the US. More broadly we discuss aspects of applying deep learning in the context of ecological modeling.

How to cite: Rammer, W. and Seidl, R.: New deep-learning based approaches for forest modeling beyond landscape scale, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-16528,, 2021.

EGU21-16531 | Presentations | US4

Better representing vegetation canopy structure in Earth System Models

Renato Braghiere

Addressing the impact of 3D vegetation structure on shortwave radiation transfer in Earth System Models (ESMs) is important for accurate weather forecasting, carbon budget estimates, and climate predictions. While leaf-level photosynthesis is well characterized and understood, estimates of global level carbon assimilation in the literature range from 110 to 175 PgC.yr-1. I will explore how neglecting canopy structure leads to significant uncertainties in shortwave radiation partitioning, as well as second order derived canopy properties, such as leaf area index (LAI). I will also cover how modeled carbon assimilation of the terrestrial biosphere is impacted when a satellite derived clumping index is incorporated into the UKESM. Finally, I will touch on how the clumping index might be integrated into hyperspectral ESMs to explore the theoretical relationship between canopy structure and photosynthesis.

How to cite: Braghiere, R.: Better representing vegetation canopy structure in Earth System Models, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-16531,, 2021.

EGU21-16569 | Presentations | US4

General Ecosystem Models, moving towards modelling responses and effects of whole ecosystems

Mike Harfoot, Derek Tittensor, Selwyn Hoeks, Jens Krause, Almut Arneth, Chris Doughty, and Andrew Abraham

Ecosystems are facing unprecedented pressures as a result of human activities. At the same time, ecology as a discipline is increasingly demanding more mechanistic understanding of what causes observed ecological patterns, in part for the development of the science but also to help mitigate impacts. Here, I will present the Madingley Model (, a General Ecosystem Model that aims to provide a mechanistic understanding of how ecosystems, on land and in the seas, are structured and how they function, and for how anthropogenic changes might alter that structure and function. I will discuss the model’s current capabilities, how it is being used, and highlight some necessary and exciting future directions for development.

How to cite: Harfoot, M., Tittensor, D., Hoeks, S., Krause, J., Arneth, A., Doughty, C., and Abraham, A.: General Ecosystem Models, moving towards modelling responses and effects of whole ecosystems, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-16569,, 2021.

EGU21-16600 | Presentations | US4 | Highlight

Interactive Simulation of 3-D Ecoclimates

Miłosz Makowski, Torsten Hädrich, Dominik Michels, Sören Pirk, Wojtek Palubicki, and Weronika Skowronska

Over the last years, the role of forests in climate change has received increased attention. This is due to the observation that not only the atmosphere has a principal impact on vegetation growth but also that vegetation is contributing to local variations of weather resulting in diverse microclimates. The interconnection of plant ecosystems and weather is described and studied as ecoclimates. In this work we simulate ecoclimates by modeling (1) the local climate-response of individual plants in large-scale ecosystems, (2) the vegetation impact on the atmosphere, and (3) the soil hydrology. We employ interactive state-of-the-art methods for simulating ecosystem growth and weather dynamics to enable a realistic animation of vegetation growth, plant competition and cooperation mediated by light and soil water, as well as cloud transitions. Our plant ecosystem model simulates the growth of individual trees with branch-level geometry. We couple an ecosystem with a weather model to locally sample weather variations over time, which enables us to simulate the long-term climate-response of individual tree models. Simultaneously, the composition of an ecosystem affects the development of weather: individual trees vary in how they release vapor or transfer heat to the air. Our framework allows us to interactively explore the growth- and climate-response of individual trees and of an ecosystem as a whole.

How to cite: Makowski, M., Hädrich, T., Michels, D., Pirk, S., Palubicki, W., and Skowronska, W.: Interactive Simulation of 3-D Ecoclimates, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-16600,, 2021.

US5 – Faults, Rivers and Topography: in memory of Patience A. Cowie

EGU21-110 | Presentations | US5

Patience Cowie and the Inception of Modern Fault Mechanics:  A Recollection

Christopher H. Scholz

Patience Cowie’s PhD thesis, conducted with me at Lamont, resulted in three papers, published in 1992, that laid the groundwork for the modern era of fault mechanics studies. In the first paper1 she reasoned that a cohesive zone model provided a plausible model of fault grown provided that the width of the cohesive zone scales linearly with fault length. In that case, the Griffith instability is avoided and faults grow self-similarly in quasistatic equilibrium. This model is consistent with the existence of faults of all sizes in which displacement scales linearly with length and the fault grows by the breakdown of a damage zone at the fault tip. In the second paper2 she showed that the then existing data for fault displacement and length were consistent with linear scaling for faults rupturing rock of similar strength. In the third paper3 she combined the earthquake slip/length scaling law with that fault scaling law to show how faults can grow by the accumulation of slip from earthquakes.

In the subsequent thirty years much more work has been done to expand on these themes pioneered by Patience. Here I share some memories of working with Patience in those formative years.


1          Cowie, P. A. & Scholz, C. H. Physical explanation for the displacement-length relationship of faults using a post-yield fracture mechanics model. J.       Struct. Geol. 14, 1133-1148 (1992).

2          Cowie, P. A. & Scholz, C. H. Displacement-length scaling relationship for faults: data synthesis and discussion. J. Struct. Geol. 14, 1149-1156 (1992).

3          Cowie, P. A., and Scholz, C.H. Growth of faults by accumulation of seismic slip. J. Geophys. Res. 97(B7), 11085-11095 (1992b).

How to cite: Scholz, C. H.: Patience Cowie and the Inception of Modern Fault Mechanics:  A Recollection, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-110,, 2021.

Patience Cowie was a truly outstanding scientist whose research spanned several disciplines of structural geology and tectonics. She made a lasting contribution to every discipline she published in and as well as academic advances, produced significant impacts in the hydrocarbon industry and earthquake hazard assessment. Her research in fault mechanics and fault population was a genuine game-changer. The implications of her work for predicting fault patterns and linkage have been crucial for the interpretation of 3D seismic data, and for examining the interplay between faults and the basins they bound and sediments they host. More recently she explored relationships between fault geometry, slip rate and recurrence intervals along seismically active faults, with important implications for earthquake hazard assessment.

Patience’s drive to constrain physical explanations of the underlying dynamics of Earth processes meant her numerical modelling was always firmly grounded in field observations. Her models incorporated the effects of stress in time and space as fault system evolved, but always underpinned by geometric and kinematic observations in the field. She loved fieldwork and her joy at the beauty of geological structures was infectious and inspiring.  

How to cite: Shipton, Z.: A retrospective of the work of Patience Cowie: the interaction of faults in space and time and their influences on subsurface fluid flow, surface processes and earthquakes, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-7780,, 2021.

EGU21-15774 | Presentations | US5

Fault evolution, scaling relationships and hazard

Joanna Faure Walker, Francesco Iezzi, and Gerald Roberts

Changes in fault geometry, throw-rates and slip-rates along the length of a fault are crucial for understanding fault evolution and interaction and need to be incorporated in interpretation of fault scaling relationships and earthquake hazard assessments. Normal fault examples from Iceland and Italy provide examples of soft linkage, breach faults, and bends in faults that can be used to investigate fault growth at different stages of fault linkage. We find that at all stages of fault linkage studied, bends in strike along a fault affect throw-rate profiles along the fault. Crucially, for fault-based seismic hazard assessment, we need to consider how we interpret throw-rate and slip-rate profiles along a fault because how we interpret slip-rate profiles will impact moment release calculations and hence recurrence intervals. We therefore need detailed data regarding fault geometry and slip-rates to inform fault-based seismic hazard assessments, uncertainties and where further study is needed.

How to cite: Faure Walker, J., Iezzi, F., and Roberts, G.: Fault evolution, scaling relationships and hazard, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-15774,, 2021.

EGU21-1179 | Presentations | US5

Towards a better understanding of the impact of erosion on fault slip and seismicity

Philippe Steer, Louise Jeandet-Ribes, Rodolphe Cattin, Martine Simoes, Nadaya Cubas, Harsha S. Bhat, J. Bruce H. Shyu, Maxime Mouyen, Odin Marc, and Niels Hovius

Tectonics, climate and surface processes dictate the evolution of Earth’s surface topography. Topographic change in turn influences lithospheric deformation, but the temporal and spatial scales at which this feedback can be effective remains an open issue. Here, we make a synthesis of recent developments investigating how erosion impacts the stress-loading of faults and potentially induces some earthquakes. We first show, using an elastic model for the lithosphere, that erosion rates of ca 0.1–20 mm.yr−1, as documented in active compressional orogens, can raise the Coulomb stress by ca 0.1–10 bar on the nearby thrust faults over an earthquake cycle, by changing both the normal and tangential stress. This model also suggests that short-lived but intense erosional events can represent a prominent mechanism for inter-seismic stress loading of faults near the surface. Indeed, we demonstrate that typhoon Morakot in 2009, which triggered numerous landslides, was followed by a step increase in the shallow (< 15 km depth) earthquake frequency and in the b-value, lasting at least 2.5 years. These observations suggest that the progressive removal of landslide debris by rivers from southern Taiwan has increased the crustal stress rate and earthquake activity. Last, we use QDYN, a quasi‐dynamic numerical model of earthquake cycles to investigate the effect of a large erosional event, such as typhoon Morakot, on seismicity. We show that erosional events with a duration shorter than the duration of an earthquake cycle can significantly increase the seismicity rate, even for small stress changes. Consistent with the increase in the b-value observed after typhoon Morakot, our results also show that large erosional events with a period similar to the earthquake nucleation timescale can change earthquake size distribution by triggering more small events. Overall, these modelling results and observations highlight that short-lived but intense erosional events can lead to perceptible changes in shallow seismicity, affecting both earthquake frequency and size-distributions.

How to cite: Steer, P., Jeandet-Ribes, L., Cattin, R., Simoes, M., Cubas, N., Bhat, H. S., Shyu, J. B. H., Mouyen, M., Marc, O., and Hovius, N.: Towards a better understanding of the impact of erosion on fault slip and seismicity, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-1179,, 2021.

The Corinth Rift, Greece, is a young (~5 Ma) sea-level controlled rift and one of the most rapidly extending areas on Earth. The unique combination of high strain and sedimentation rate with a closed drainage system and the well preserved syn-rift sedimentary record makes the Corinth Rift an ideal laboratory for understanding interactions between surface processes and tectonics and their implications for syn-rift stratigraphy.

The Corinth Rift has exceptional onshore and offshore field data coverage and as such it represents one of the best natural examples for model calibration. To this end, offshore sediment packages mapped from seismic reflection data were used to validate the surface process model pyBadlands, by comparing the total real and modeled sediment volumes and deposition patterns over the past 130 kyr.  Our results shed light on the impact of tectonic forcing on sediment fluxes by showing that sediment supply to the rift is not primarily controlled by relief development, but instead by tectonically-driven tilting of the landscape. This is the first time that this has been demonstrated for a natural system and challenges the view that relief is a key control on catchment averaged erosion rates.

Moreover, recent drilling data from IODP Expedition 381 in the Corinth Rift generated a complete record of the syn-rift sequence offshore and provided the first age constraints to enable us to resolve sediment accumulation rates with high temporal resolution. The new cores record climate-driven cyclic variations in the basin paleoenvironment, alternating between glacial/isolated and interglacial/marine periods. A key finding is that sedimentation rates are markedly increased during glacial/isolated periods. Furthermore, bed frequency and bed thicknesses show significant stratigraphic variability and highlight the dominance of gravity flow sedimentation which represents > 60% of the total sedimentation during the last glacial-interglacial cycle.

This extraordinary offshore drilling data when combined with surface processes modelling will provide an unprecedented opportunity to address the challenge of resolving tectonic versus climatic controls on sediment production and stratigraphic development within rift basins.

How to cite: Pechlivanidou, S.: From surface processes modelling to high-resolution drilling record: resolving key controls on sediment production and stratigraphic development in the Corinth Rift, Greece, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-1195,, 2021.

CC BY 4.0