NH – Natural Hazards

NH1.1 – Flood risk modelling and assessment (with a special focus on uncertainty)

EGU2020-732 | Displays | NH1.1

Probabilistic Flood Hazard Maps at Ungauged Locations Using Multivariate Extreme Values Approach

Kiran Kezhkepurath Gangadhara and Srinivas Venkata Vemavarapu

Flood hazard maps are essential for development and assessment of flood risk management strategies. Conventionally, flood hazard assessment is based on deterministic approach which involves deriving inundation maps considering hydrologic and hydraulic models. A flood hydrograph corresponding to a specified return period is derived using a hydrologic model, which is then routed through flood plain of the study area to estimate water surface elevations and inundation extent with the aid of a hydraulic model. A more informative way of representing flood risk is through probabilistic hazard maps, which additionally provide information on the uncertainty associated with the extent of inundation. To arrive at a probabilistic flood hazard map, several flood hydrographs are generated, representing possible scenarios for flood events over a long period of time (e.g., 500 to 1000 years). Each of those hydrographs is routed through the flood plain and probability of inundation for all locations in the plain is estimated to derive the probabilistic flood hazard map. For gauged catchments, historical streamflow and/or rainfall data may be used to determine design flood hydrographs and the corresponding hazard maps using various strategies. In the case of ungauged catchments, however, there is a dearth of procedures for prediction of flood hazard maps. To address this, a novel multivariate regional frequency analysis (MRFA) approach is proposed. It involves (i) use of a newly proposed clustering methodology for regionalization of catchments, which accounts for uncertainty arising from ambiguity in choice of various potential clustering algorithms (which differ in underlying clustering strategies) and their initialization, (ii) fitting of a multivariate extremes model to information pooled from catchments in homogeneous region to generate synthetic flood hydrographs at ungauged target location(s), and (iii) routing of the hydrographs through the flood plain using LISFLOOD-FP model to derive probabilistic flood hazard map. The MRFA approach is designed to predict flood hydrograph related characteristics (peak flow, volume and duration of flood) at target locations in ungauged basins by considering watershed related characteristics as predictor/explanatory variables. An advantage of the proposed approach is its ability to account for uncertainty in catchment regionalization and dependency between all the flood hydrograph related characteristics reliably. Thus, the synthetic flood hydrographs generated in river basins appear more realistic depicting the observed dependence structure among flood hydrograph characteristics. The approach alleviates several uncertainties found in conventional methods (based on conceptual, probabilistic or geomorphological approaches) which affect estimation of flood hazard. Potential of the proposed approach is demonstrated through a case study on catchments in Mahanadi river basin of India, which extends over 141,600 km2 and is frequently prone to floods. Comparison is shown between flood hazard map obtained based on true at-site data and that derived based on the proposed MRFA approach by considering the respective sites to be pseudo-ungauged. Coefficient of correlation and root mean squared error considered for performance evaluation indicated that the proposed approach is promising.

How to cite: Kezhkepurath Gangadhara, K. and Venkata Vemavarapu, S.: Probabilistic Flood Hazard Maps at Ungauged Locations Using Multivariate Extreme Values Approach, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-732,, 2020.

EGU2020-6376 | Displays | NH1.1

Impact of large-scale future floods on the railway system

Weiping Wang, Saini Yang, Huijun Sun, Jianjun Wu, and Jianxi Gao

Increasing flood risk was caused by expanding climate change. The floods directly or indirectly disrupt the railway system and arise a significant negative impact on our social-economic system. This study developed an integrated approach to explore the impact of large-scale future floods on railway system. Firstly, A three layered traffic flow simulation model was constructed to study propagation and amplification effects of component failure after the event of flooding in the system. Secondly, future runoff scenarios were produced by using five global climate models and three different representative concentration pathways. The future floods was simulated by using CaMa-Flood model after inputting future runoff scenarios. Furthermore, we imposing simulated future floods into traffic simulation system and develop two measurements to evaluate the impact of floods on the railway system as the perspective of the entire system. Here we explore the impact of floods on the real-world highway network of China. The results illustrate that: (i) Unprecedented uncertainty. The damage of the flood to the railway system is not linearly and positively correlated with representative concentration pathway and the year within different global climate models; Floods in different years have different impacts in connections among regions; (ii) Unacceptable damage. 59.76 % of railway segments inundated and 98.61461% of large cities could not be reached by extreme floods. These results have critical policy implications for the transport sector in reference to railway location and design, railway network optimization and protection and can be also easily adapted to analyze other spatial damages for valuable protection suggestions.

How to cite: Wang, W., Yang, S., Sun, H., Wu, J., and Gao, J.: Impact of large-scale future floods on the railway system, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-6376,, 2020.

Catastrophic flooding resulting from extreme tropical cyclones has occurred more frequently and drawn great attention in recent years in China. Coastal cities are particularly vulnerable to flood under multivariable conditions, such as heavy precipitation, high sea levels, and storms surge. In coastal areas, floods caused by rainstorms and storm surges have been one of the most costly and devastating natural hazards in coastal regions. Extreme precipitation and storm tide are both inducing factors of flooding and therefore their joint probability would be critical to determine the flooding risk. Usually, extreme events such as tidal level, storm surges, precipitation occur jointly, leading to compound flood events with significantly higher hazards compared to the sum of the single extreme events. The purpose of this study is to improve our understanding of multiple drivers to compound flooding in shanghai. The Wind Enhance Scheme (WES) model characterized by Holland model is devised to generate wind "spiderweb" both for historical (1949-2018) and future (2031-2060, 2069-2098) tropical cyclones. The tidal level and storm surge model based on Delft3D-FLOW is employed with an unstructured grid to simulate the change of water level. For precipitation, maximum value between tropical cyclone events is selected. Following this, multivariate Copula model would be employed to compare the change of joint probability between tidal level, storm surge and heavy precipitation under climate change, taking into account sea-level rise and land subsidence. Finally, the impact of tropical cyclone on the joint risk of tidal, storm surge and heavy precipitation is investigated. 

How to cite: Xu, H.: Compound impact of rainfall, tidal level and storm surge on flood risk from tropical cyclones in the coastal area of shanghai, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-6518,, 2020.

EGU2020-7334 | Displays | NH1.1 | Highlight

Probabilistic Flood Loss Models for Companies

Lukas Schoppa, Tobias Sieg, Kristin Vogel, Gert Zöller, and Heidi Kreibich

Flood risk assessment strongly relies on accurate and reliable estimation of monetary flood loss. Conventionally, this involves univariable deterministic stage-damage functions. Recent advancements in the field promote the use of multivariable probabilistic loss estimation models which consider damage controlling variables beyond inundation depth. Although companies contribute significantly to total loss figures, multivariable probabilistic modeling approaches for companies are lacking. Scarce data and heterogeneity among companies impedes the development of novel company flood loss models.

We present three multivariable flood loss estimation models for companies that intrinsically quantify prediction uncertainty. Based on object-level loss data (n=1306), we comparatively evaluate the predictive performance of Bayesian networks, Bayesian regression and random forest in relation to established stage-damage functions. The company loss data stems from four post-event surveys after major floods in Germany between 2002 and 2013 and comprises information on flood intensity, company characteristics and private precaution. We examine the performance of the candidate models separately for losses to building, equipment, and goods and stock. Plausibility checks show that the multivariable models are able to identify and reproduce essential relationships of the flood damage processes from the data. The comparison of the prediction capacity reveals that the proposed models outperform stage-damage functions clearly while differences among the multivariable models are small. Even though the presented models improve the accuracy of loss predictions, wide predictive distributions underline the necessity for the quantification of predictive uncertainty. This applies particularly to companies, for which the heterogeneity and variation in the loss data are more pronounced than for private households. Due to their probabilistic nature, the presented multivariable models contribute towards a transparent treatment of uncertainties in flood risk assessment.

How to cite: Schoppa, L., Sieg, T., Vogel, K., Zöller, G., and Kreibich, H.: Probabilistic Flood Loss Models for Companies, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-7334,, 2020.

EGU2020-7632 | Displays | NH1.1 | Highlight

Global Flood Model: Revolutionising Flood Catastrophe Modelling

Paul Dunning, Kirsty Styles, Daniel Evans, and Stephen Hutchings

Catastrophe models are well established tools, traditionally used by the re/insurance industry to assess the financial risk to insured property (“exposure”) associated with natural perils. Catastrophe modelling is challenging, particularly for flood perils over large geographical scales, for a number of reasons. To adequately capture the fine spatial variability of flood depth, a flood catastrophe model must be of high spatial resolution. To validly compare estimates of risk obtained from catastrophe models for different geographical regions, those models must be built from geographically consistent data. To compare estimates of risk between any given collection of geographical regions globally, global coverage is required.

Traditional catastrophe models struggle to meet these requirements; compromises are made, often for performance reasons.  In addition, traditional models are typically static datasets, built in a discrete process prior to their use in exposure risk assessment. Scientific assumptions are therefore deeply embedded; there is little scope for the end user to adjust the model based on their own scientific knowledge.

This research presents a new and better approach to catastrophe modelling that addresses these challenges and, in doing so, has allowed creation of the world’s first global flood catastrophe model.

JBA’s Global Flood Model is facilitated by a technological breakthrough in the form of JBA’s FLY Technology. The innovations encoded in FLY have enabled JBA to create a model capable of consistent global probabilistic flood risk assessment, operating at 30m resolution and supported by a catalogue of 15 million distinct flood events (both river and surface water). FLY brings a model to life dynamically, from raw flood hazard data, simultaneously addressing the user configurability and performance challenges.

Global Flood Model and FLY Technology will be of interest to those involved in financial, economic or humanitarian risk assessment, particularly in and between countries and regions not covered by flood catastrophe models to date. The detail of how they work will be covered here, and their power in facilitating consistent global flood risk assessment will be demonstrated.

How to cite: Dunning, P., Styles, K., Evans, D., and Hutchings, S.: Global Flood Model: Revolutionising Flood Catastrophe Modelling, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-7632,, 2020.

EGU2020-8000 | Displays | NH1.1 | Highlight

Re-assessing extreme sea level events through interplay of tides and storm surges

Stephen Outten, Tobias Wolf, Fabio Mangini, Linling Chen, and Jan Even Nilsen

Flooding events pose an ever increasing threat in a warming world. Safety standards for buildings and infrastructure are often based on past observations of local sea level, as measured by tide gauges and remote sensing systems. However, sea level at a given location is not an isolated property and is determined by a combination of factors. For extreme sea level events, there are two factors that of particular importance: the astronomical tide, and storm surges. In this work, we analysed measurements from 21 stations in the Norwegian tide gauge network, disentangling the factors contributing to the previously observed extreme events.

By separating the observed sea level into a tidal component and a storm surge component, we found that in many cases the observed extreme sea level events were caused by an extreme storm surge coinciding with only a moderate tide, or an extreme tide coinciding with only a moderate storm surge. This raises the possibility of a ‘super-flooding’ event, where an extreme storm surge may occur with an extreme tide. Even in the short records examined in this study (less than 40 years), the combination of the highest observed tide with the highest observed storm surge would greatly exceed in the 1000-year return level event at many locations. This is often used as a national standard for critical infrastructure.  

We further complement the work by analysing the storm tracks close to Norway. By relating the storm surges with the individual storms giving rise to them, we found that many storm surges during extreme sea level events were related to cyclones of only moderate intensity. Combined with the previous findings, this work suggests the need to assess extreme sea level return values for future construction and infrastructure planning as the result of a multi-variable system. This is in contrast to basing such assessments on the single variable of observed sea level as it is done today.

How to cite: Outten, S., Wolf, T., Mangini, F., Chen, L., and Nilsen, J. E.: Re-assessing extreme sea level events through interplay of tides and storm surges, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-8000,, 2020.

Two case studies are considered in the UK, where uncertainty and drivers of coastal flood risk are explored through modelling and visualisations. Visualising the impact of uncertainty is a useful way of explaining the potential range of predicted or simulated flood risk to both expert and non-expert stakeholders.

Significant flooding occurred in December 2013 and January 2017 at Hornsea on the UK East Coast, where storm surge levels and waves overtopped the town’s coastal defences. Uncertainty in the potential coastal flooding is visualised at Hornsea due to the range of uncertainty in the 100-year return period water level and in the calculated overtopping due to 3 m waves at the defences. The range of uncertainty in the simulated flooding is visualised through flood maps, where various combinations of the uncertainties decrease or increase the simulated inundated area by 58% and 82% respectively.

Located at the mouth of the Mersey Estuary and facing the Irish Sea, New Brighton is affected by a large tidal range with potential storm surge and large waves. Uncertainty in the coastal flooding at the 100-year return period due to the combination of water levels and waves is explored through Monte-Carlo analysis and hydrodynamic modelling. Visualisation through flood maps shows that the inundation extent at New Brighton varies significantly for combined wave and surge events with a joint probability of 100 years, where the total flooded area ranges from 0 m2 to 10,300 m2. Waves are an important flood mechanism at New Brighton but are dependent on high water levels to impact the coastal defences and reduce the effective freeboard. The combination of waves and high-water levels at this return level not only determine the magnitude of the flood extent but also the spatial characteristics of the risk, whereby flooding of residential properties is dominated by overflow from high water levels, and commercial and leisure properties are affected by large waves that occur when the water level is relatively high at the defences.

How to cite: Maskell, J.: Uncertainty in coastal flooding: modelling and visualisation, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-8390,, 2020.

EGU2020-10879 | Displays | NH1.1

An inter and transdisciplinary participatory approach to assess the current flood risk management practices in Ghana

Adrian Almoradie, Mariana Madruga de Brito, and Mariele Evers

The understanding of the multifaceted nature of flood risk management (FRM) of a country requires the consideration of both social, technical as well as governance aspects. The inclusion of these components in the analysis and assessment of FRM allows comprehending the veracity of its interdependencies, its strengths and weakness that would, in turn, aid in improving the current system.

This paper presents an inter and transdisciplinary and participatory multi-method participatory approach to promptly assess Ghana’s current FRM practices, describing the current gaps and opportunities for improving FRM. Here, we describe the challenges on its institutional, governance and implementation, scientific, technical and social capacity levels and potential ways forward. The methodological  approach comprised a systematic literature review of 53 peer-reviewed articles, stakeholder analysis, engagement of stakeholders on workshops through focus group discussion and collaborative mapping, interviews with key individual stakeholders, and household surveys with 1,479 citizens living in flood prone areas. The stakeholders were identified and categorized into governance and implementation, academia and research and security agencies.

Results show that stakeholders have diverse and even contradictory views regarding FRM in Ghana. Overall, the findings indicate that: (1) the most critical regions are Accra, Kumasi, and the White Volta river basin, (2) the most crucial aspects for reducing vulnerability and exposure are related with high population density, social hotspots and location of Critical Infrastructure, (3) FRM  are unsustainable and unintegrated and it heavily relies on short-term projects and external funders, (4) reliable data is scarcily available and communities need to be engage more in the planning and provision of information and data, (5) there are weaknesses in flood early warning systems (FEWS), institutional collaborations, human capacity, trained FRM professionals and problems in policy implementation, (6) the most important vulnerability criteria are the existence of FEWS, disaster relief agencies, areas with a high density of children and poverty rate, (7) the interviewed communities in Accra and Kumasi claimed that flood disasters are caused mainly by human activities and interventions.

The applied participatory multi-method approach proved to be useful to capture the factual situation of the FRM in Ghana, this was shown when cross-referencing the results of the different methods. The use of a participatory and inter and transdisciplinary approach allowed capturing a multitude of views as well as the stakeholders needs and requirements in terms of FRM. The co-production of knowledged allowed improving the credibility, salience and legitimacy of project outputs.

How to cite: Almoradie, A., Madruga de Brito, M., and Evers, M.: An inter and transdisciplinary participatory approach to assess the current flood risk management practices in Ghana, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-10879,, 2020.

EGU2020-11562 | Displays | NH1.1

Towards fast large-scale flood simulations using 2D Shallow water modelling with depth-dependant porosity

Vita Ayoub, Carole Delenne, Patrick Matgen, Pascal Finaud-Guyot, and Renaud Hostache

In hydrodynamic modelling, the mesh resolution has a strong impact on run time and result accuracy. Coarser meshes allow faster simulations but often at the cost of accuracy. Conversely, finer meshes offer a better description of complex geometries but require much longer computational time, which makes their use at a large scale challenging. In this context, we aim to assess the potential of a two-dimensional shallow water model with depth-dependant porosity (SW2D-DDP) for flood simulations at a large scale. This modelling approach relies on nesting a sub-grid mesh containing high-resolution topographic and bathymetric data within each computational cell via a so-called depth-dependant storage porosity. It enables therefore faster simulations on rather coarse grids while preserving small-scale topography information. The July 2007 flood event in the Severn River basin (UK) is used as a test case, for which hydrometric measurements and spatial data are available for evaluation. A sensitivity analysis is carried out to investigate the porosity influence on the model performance in comparison with other classical parameters such as boundary conditions.

How to cite: Ayoub, V., Delenne, C., Matgen, P., Finaud-Guyot, P., and Hostache, R.: Towards fast large-scale flood simulations using 2D Shallow water modelling with depth-dependant porosity, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-11562,, 2020.

EGU2020-12405 | Displays | NH1.1

Assessment of the risk of destabilization of vehicles at crossing points between streams and roads

Ricardo Andres Bocanegra Vinasco and Félix Francés

River floods can cause the destabilization of vehicles and vehicles can increase the negative impacts of floods when they are mobilized by the flow, causing economic and life losses. Because of this, integral flood management requires the identification and assessment of the risk to which vehicles are subjected at the crossing points between water currents and roads. In the present investigation a methodology was developed to calculate this risk based on the characteristics of vehicles, floods and traffic. The risk at each stream crossing is calculated by means of the statistical integral of the vehicle vulnerability given the actual exposition and hazard.


Hazard corresponds to the probability that flow causes the destabilization of each type of car and is determined from the hydrodynamic characteristics of the floods and the implementation of a stability criterion for partially submerged cars, through which a hazard index is established. Hazard is obtained through the combination of the probability that the flood event occurs with the values that the hazard index would take. The vulnerability of a given type of car is determined by means of a damage function defined from the values of the hazard index. The exposure is established based on the traffic characteristics and the driver behavior.


The methodology developed was applied in the municipality of Godelleta (Spain), finding that in approximately a quarter of the 25 intersections between streams and roads, the risk of vehicles due to flooding is relatively high, since it exceeds 0.2 vehicles per year. In approximately half of the intersections the risk is relatively low since it is less than 0.1 vehicles per year. Additionally, it was found that the risk of vehicles in stream crossings due to flooding is highly sensitive to the magnitude of the water level from which drivers decide to interrupt vehicle traffic through flooded crossing. The magnitude of the risk grows as drivers assume less conservative behavior, that is, when they decide to drive with higher water levels.

Key words

Risk of vehicles due to floods

Stability of cars partially submerged

Vulnerability of vehicles to floods

How to cite: Bocanegra Vinasco, R. A. and Francés, F.: Assessment of the risk of destabilization of vehicles at crossing points between streams and roads, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-12405,, 2020.

Hydraulic models are increasingly used to assess the flooding hazard. However, all numerical models are affected by uncertainties, related to model parameters, which can be quantified through Uncertainty Quantification (UQ) and Global Sensitivity Analysis (GSA). In traditional methods of UQ and GSA, the input parameters of the numerical models are considered to be independent which is actually rarely the case. The objective of this work is to proceed with UQ and GSA methods considering dependent inputs and comparing different methodologies. At our knowledge, there is no such application in the field of 2D hydraulic modelling.

At first the uncertain parameters of the hydraulic model are classified in groups of dependent parameters. Within this aim, it is then necessary to define the copulas that better represent these groups. Finally UQ and GSA based on copulas are performed. The proposed methodology is applied to the large scale 2D hydraulic model of the Loire River. However, as the model computation is high time-consuming, we used a meta-model instead of the initial model. We compared the results coming from the traditional methods of UQ and GSA (i.e. without taking into account the dependencies between inputs) and the ones coming from the new methods based on copulas. The results show that the dependence between inputs should not always be neglected in UQ and GSA.

How to cite: Pheulpin, L. and Bacchi, V.: Uncertainty quantification and global sensitivity analysis with dependent inputs: Application to the 2D hydraulic model of the Loire River, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-18939,, 2020.

EGU2020-19000 | Displays | NH1.1

Uncertainty in the modelling of large scale flood events in the Barotse floodplain, Zambia

Tom Willis, Mark Smith, Donall Cross, Andrew Hardy, Georgina Ettritch, Happiness Malawo, Mweemba Sinkombo, Cosmas Chalo, and Chris Thomas

The Barotse floodplain in the Western Province of Zambia, is a major feature of the Upper Zambezi River, covering an area of 11,000km2, and is inundated annually by a flood cycle that ranges from minimum values in September, to peak levels in April. The annual flooding of the area provides a number of challenges, and critically is a significant component of the life cycle of mosquitos, the principle vector for the transmission of malaria. A research project, FLOODMAL, has been developed to apply process based modelling approaches to the life cycle of the mosquito in the floodplain. A significant component of this approach is the development of a 1D-2D model which can be used to predict the formation of water bodies that are essential to the mosquito breeding cycle. This research presents the uncertainties associated with developing the flood model, with an emphasis on model performance through simulation time. In a typical model exercise, the calibration of input parameters are associated with ensuring that model performance is optimised for representing the peak of a flood event. This can be at the cost of providing a consistent level of model performance throughout a simulation, which is essential in this research.

Using the LISFLOOD-FP computer code, and TanDEM-X1 terrain data, a baseline model of the Barotse floodplain was developed for the 2009 and 2018 events. A set of initial model runs identified key processes to be represented in the model, including evaporation and infiltration. The calibration of the model was focused on defining parameters for surface roughness, channel roughness, evaporation, infiltration, and defining channel topography. A number of datasets were available for model calibration, such as LandSAT imagery to compare observed and modelled extent at various points throughout the year, and downstream river gauge data. To further understand the uncertainties associated with the modelling, sensitivity analysis was undertaken using an emulator- based approach to define the contribution of the input parameters to overall model variance. The results indicate that parameters that control the movement of water across the floodplain (surface roughness) are generally the most significant of the inputs at all points in the year, although the level of this significance changes at different phases.

How to cite: Willis, T., Smith, M., Cross, D., Hardy, A., Ettritch, G., Malawo, H., Sinkombo, M., Chalo, C., and Thomas, C.: Uncertainty in the modelling of large scale flood events in the Barotse floodplain, Zambia , EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-19000,, 2020.

EGU2020-19057 | Displays | NH1.1

From Flash Flood Vulnerability and Risk Assessment to Property Damage Prediction: the Value of Machine Learning

Atieh Alipour, Peyman Abbaszadeh, Ali Ahmadalipour, and Hamid Moradkhani

Flash floods, as a result of frequent torrential rainfalls caused by tropical storms, thunderstorms,
and hurricanes, are a prevalent natural disaster in the southeast U.S. (SEUS), which frequently
threaten human lives and properties in the region. According to the U.S. National Weather
Service (NWS), flash floods generally initiate within less than six hours of an intense rainfall
onset. Therefore, there is a limited chance for effective and timely decision-making. Due to the
rapid onset of flash floods, they are costly events, such that only during 1996 to 2017 flash
floods imposed 7.5 billion dollars property damage to the SEUS. Therefore, estimating the
potential economic damages as a result of flash floods are crucial for flood risk management and
financial appraisals for decision makers. A multitude of studies have focused on flood damage
modeling, few of which investigated the issue on a large domain. Here, we propose a systematic
framework that considers a variety of factors that explain different risk components (i.e., hazard,
vulnerability, and exposure) and leverages Machine Learning (ML) for flood damage prediction.
Over 14,000 flash flood events during 1996 to 2017 were assessed to analyze their characteristics
including frequency, duration, and intensity. Also, different data sources were utilized to derive
information related to each event. The most influential features are then selected using a multi
criteria variable selection approach. Then, the ML model is implemented for not only binary
classification of damage (i.e., whether a flash flood event caused any damage or not), but also for
developing a model to predict the financial consequences associated with flash flood events. The
results indicate a high accuracy for the classifier, significant correlation and relatively low bias
between the predicted and observed property damages showing the effectiveness of proposed
methodology for flash flood damage modeling applicable to variety of flood prone regions.

How to cite: Alipour, A., Abbaszadeh, P., Ahmadalipour, A., and Moradkhani, H.: From Flash Flood Vulnerability and Risk Assessment to Property Damage Prediction: the Value of Machine Learning, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-19057,, 2020.

EGU2020-21735 | Displays | NH1.1

Computational fluid dynamics (CFD) for “typical Dutch” houses failure: experiments and numerical modelling comparison.

Manuel Andrés Díaz Loaiza, Benedikt Bratz, Jeremy Bricker, and PAul Korswagen

Computational fluid dynamics (CFD)  for “typical Dutch” houses failure: experiments and numerical modelling comparison.

Authors: Andres Diaz Loaiza1, Benedikt Bratz1,2, Jeremy Bricker1 and Paul Korswagen1

1- Hydraulic Structures and Flood Risk, Technical University of Delft, 1- Technische Universität Braunschweig


Coastal and riverine floods can be a catastrophic natural hazard with importance consequences. Many of the casualties occurring during these events can be attributed to the collapse of residential houses, and it is thus required to gain knowledge about the failure mechanism of these structures. Multiple variables can lead to various flow conditions that will in turn represent different load pressures over the house; among these, the type of the material (used in the construction), the orientation angle in respect to the main flow direction, the shape of the structure, and the urban density (blockage ratio), are relevant. In the present paper, small scale experiments are compared with CFD simulations performed with openFOAM in order to obtain a numerical model than can predict different combinations of load pressures for various flood events.


The present study aims to represent different “typical Dutch” houses near or close to a dam break in which rapid high flow velocities and depths can be presented. The flow conditions and load pressures outputs are compared to physical results in order to validate the numerical model.

How to cite: Díaz Loaiza, M. A., Bratz, B., Bricker, J., and Korswagen, P.: Computational fluid dynamics (CFD) for “typical Dutch” houses failure: experiments and numerical modelling comparison., EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-21735,, 2020.

EGU2020-3200 | Displays | NH1.1

Development of Flood Hazard Map from Probabilistic Embankment Collapse Inflow

Changhee Lee, Myeong Jun Nam, and Jae Young Lee

Flood damages caused by abnormal climate changes occur frequently every year. Systems to predict and respond to disasters are required to prepare for flood damages. The embankment overflow and collapse mechanism due to the rapid increase of river water level in flood are quite complex, varied, and uncertain. In this study, changes of river embankment collapse widths and flood inflows were calculated. In this case, the MCS-based probability flood levels were used based on th hydrologcal scenario, which takes into account the uncertainty of the parameters of extreme precipitation through the abnormal frequency analysis. In addition, two-dimensional inundation analysis was performed to estimate flood depth and flood area, and to produce a probabilistic flood hazard map. By quantitatively evaluating the uncertainty of the parameters in consideration of the overall mechanism of flood occurrence, we obtained more reliable predictions of flood depth than conventional deterministic analyses.


How to cite: Lee, C., Nam, M. J., and Lee, J. Y.: Development of Flood Hazard Map from Probabilistic Embankment Collapse Inflow, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-3200,, 2020.

EGU2020-5416 | Displays | NH1.1

Cumulant lattice Boltzmann approach: an application to hydraulic risk

Silvia Di Francesco, Sara Venturi, and Martin Geier

The purpose of this work is the implementation and the application of a semi-automatic procedure for modelling flood events, based on the coupled use of a GIS subroutine and a two-dimensional (2D) lattice Boltzmann hydraulic model solving shallow water equations. The lattice Boltzmann method (LBM) with cumulant collision operator is chosen as a numerical technique for the solution of the hydrodynamic problem. The cumulant LBM is based on the use of cumulants as basis and relaxes, in the collision step, quantities (cumulants) that are Galilean invariant by construction. It overcomes the defects in Galilean invariance of the original multi relaxation times methods and it has been shown to further improve stability. An adaptation of the original formulation for a single-phase fluid is therefore proposed and developed to reproduce shallow free surface flows. Special attention is due to the wet-dry front in shallow flows; in fact, a correct simulation of such processes plays a crucial role in practical engineering studies.

The chosen mesoscopic model, thanks to the peculiar characteristic of LBM codes of being easily parallelized, could allow accurate and realistic wave prediction in a low computation time, introducing the possible application for the assessment of the hydraulic risk.

The preparation of the input data (pre-processing) and the analysis of the modelling results (post-processing) are assisted by an interchange routines using an open source GIS platform.

The proposed methodologies are tested and validated through the use of analytical solutions and experimental solutions. Moreover, the suitability of the proposed mathematical model for large scale hydraulic engineering applications is discussed through the modelling of a real flood event, highlighting the good performances of the cumulant model.

How to cite: Di Francesco, S., Venturi, S., and Geier, M.: Cumulant lattice Boltzmann approach: an application to hydraulic risk, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-5416,, 2020.

EGU2020-13319 | Displays | NH1.1

Presenting hydrological and data driven flood simulation-prediction methods to develop a decision-making model

Mohammad Zare, Guy Schumann, Felix Norman Teferle, Patrick Matgen, and Paul D. Bates

Flooding is the number one natural disaster in terms of insured and uninsured losses annually. The development of reliable methods for flood simulation have greatly improved our ability to predict floods thereby reducing damages and loss of life in flood-prone regions. However, there is still a lot of room for improvement and innovation to provide better predictions, especially for flash floods, particularly in urban areas  This is addressed in the present study, the goal of which it is to improve simulation and prediction of flash floods and to develop a spatial decision-making model for implementing flood protection measures. In this regard, different approaches for flood simulation and flood protection should be applied. The proposed methodology links flood hazard modeling, remote sensing and machine learning methods. Combining these physical models and data driven methods will result in a more reliable hybrid model that can be employed for prediction of (flash) floods and event analysis. In order to achieve the research goal of present study we: i) add more functionality to a hydrodynamic model code; ii) complement the latter with data driven methods ;iii) develop a spatial decision-making model framework for defining flood protection measures, iv) validate process-based and data driven methods, and finally v) cross-evaluate Light Detection And Radar (LiDAR) topography with available local super-resolution drone data to assess the ability to incorporate local flood defenses into the models. The most important outcome is the creation of valuable flood maps in areas where it matters - while accounting for effects of land use and climate change. This will serve scientists as well as land and risk management authorities with better actionable flood risk information in locations where people and assets are located and in danger. It also develops innovative methodologies for estimating the changing risk from flash floods based on land use scenarios and climate change projections. Moreover, developing spatial multi-criteria decision making (SMCDM) can help decision makers to determine suitable locations and methods for flood protection measures. These methods will be particularly valuable in the context of solving current challenges of accounting for and mitigating flash floods and the effects of climate change.

How to cite: Zare, M., Schumann, G., Teferle, F. N., Matgen, P., and Bates, P. D.: Presenting hydrological and data driven flood simulation-prediction methods to develop a decision-making model , EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-13319,, 2020.

EGU2020-13387 | Displays | NH1.1

A Stable and Efficient Flood Routing Model Based on Unstructured Grid

Shan Zhou and Hongchang Hu

Godunov-type schemes are widely applied to solve shallow water equations. In this study, a novel non-negative water depth Multislope MUSCL reconstruction method is incorporated into a two-dimensional unstructured cell-centered Godunov-type finite volume model to simulate shallow water flows, It is verified that the method performs well in avoiding non-physical oscillation and also has well-balanced performance by simulate three test cases. Due to the limitation of CFL conditions, mesh refinement will greatly increase the computational cost. In this study, A Local Time Stepping(LTS) strategy is specifically designed to greatly improve the computational efficiency. In addition, in order to make the model suitable for more application scenarios, we have realized the coupling of one-dimensional and two-dimensional models. Based on the above three improvements, we have developed a stable and efficient flood routing model.

How to cite: Zhou, S. and Hu, H.: A Stable and Efficient Flood Routing Model Based on Unstructured Grid, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-13387,, 2020.

A high-resolution Digital Terrain Model 5m x 5m, land use characteristics and a validated output hydrograph from an extreme rainfall event were used as input to the coupled 1D/2D HEC-RAS hydraulic model in order to obtain the flooded area extent at the downstream segment of a small basin in the island of Crete. A spatially varying Manning’s roughness coefficient n was used to identify the differences between land coverage for the channel bed and the floodplain. Lateral structures were designed along the left and right overbanks of the stream, connecting the 1D stream flow with the 2D flow areas. The weir coefficient, used to convey the flow above the lateral structures, was also chosen for model validation in the control cross section. Detailed flood hazard mapping at the peak discharge was produced, along with the flood depths at times before and after the heavy precipitation event, in order to obtain the time evolution of the flooded area extent. The results obtained by the 1D hydraulic model are limited in their 2D lateral output that is crucial to the floodplain extent. The 1D/2D provides more detailed output concerning the flood extent at the peak discharge, as well as the maximum water depths and velocities at every grid point of the computed mesh. Defining accurate flood inundated areas is of utmost importance in civil protection agencies in order to initiate a proper early flood warning. At the same time, each EU Member State country is required to produce flood hazard maps according to EU Floods Directive at the river basin level. These 1D/2D simulation results can be beneficial in the aforementioned requirements for low probability extreme floods’ basin management.

How to cite: Sarchani, S. and Tsanis, I.: Modelling the flooded area extent at the downstream segment of a small basin through a coupled 1D/2D hydraulic model, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-13977,, 2020.

EGU2020-16441 | Displays | NH1.1

Evaluation of two automated inundation-mapping methods

Nabil Hocini, Eric Gaume, Olivier Payrastre, François Bourgin, Philippe Davy, Dimitri Lague, Frédéric Pons, and Léa Poinsignon

Flash Floods cause significant material and human damage worldwide. In France, they frequently hit small rivers of the Mediterranean area, often inducing catastrophic consequences.

Considering the large number of possibly affected small watercourses, the use of automated flood-mapping methods may be of great help for the identification of the possibly affected areas and the prediction of the potential consequences of this type of floods.

In 2019, a first evaluation of three automated inundation-mapping methods, directly implemented on high-resolution Digital Terrain Models (DTM) was presented ( The automatically retrieved flood extent maps were compared with simulated reference maps from local expert studies.        

As a continuation of this work, an application of the two best performing of these methods (1D caRtino approach and 2D Floodos approach), is presented here for the simulation of  three recent flash flood events:

  • The 15th of June 2010 flood on the Argens watershed: 25 deaths, more than 1 billion € of economic damage, 585 km of affected and simulated rivers.
  • The 3rd – 4th, of october 2015 floods in the French Riviera: 20 deaths, and 600 million € of economic damage, 131 km of affected and simulated rivers.
  • The 15th - 16th of October 2018 flood on the Aude watershed: 15 deaths, approximatively 300 million € of economic damage, 569 km of affected and simulated rivers.

At first, the peak discharges for each reach of the stream network are estimated with a hydrological model (CINECAR), calibrated against discharge values based on extensive post-event surveys. The hydraulic simulations with the two methods are then run for each reach separately in steady-state regime, based on estimated peak discharges, to obtain simulated flood maps at the reach scale that are then combined to obtain a flood extent map for the simulated event. The computation times are calculated for the two methods and compared.

The simulation results are compared with observed flood extent maps and high water marks. The flood extent maps are compared based on a critical success index criterion (CSI), showing an overall very good correspondence. The simulated water levels show a difference of less than 50 cm with high water marks in most cases.

Finally, a sensitivity analysis to the quality of DTM input information and roughness coefficients is presented.

How to cite: Hocini, N., Gaume, E., Payrastre, O., Bourgin, F., Davy, P., Lague, D., Pons, F., and Poinsignon, L.: Evaluation of two automated inundation-mapping methods, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-16441,, 2020.

In this work, a methodology for quantifying the relative impact of hydrological and hydraulic modelling parameterizations on uncertainty of inundation maps has been developed and applied in the Marta river basin, central Italy. A lumped rainfall-runoff forced by a synthetic hyetograph derived from regionalized IDF curves and a Quasi-2D hydraulic model were adopted to delineate the flood hazard maps related to different return periods. The uncertainty related to the design rainfall estimation method, given by the limited length of the time series from which the IDF curves fitted, was considered adopting a Monte Carlo approach.  On the other hand, the uncertainty related to floodplain roughness was considered adopting literature values. The above mentioned methodologies for representing both uncertainties were applied simultaneously and separately. Results, expressed in terms of variability of simulated flood extents and flow depths, suggest a significant predominance of the uncertainty related to hydrological modelling as respect to the hydraulic modelling.

How to cite: Volpi, E., Annis, A., Nardi, F., and Fiori, A.: Is hydraulic modelling parametrization the major source of variability in flood hazard assessment? Insight into hydrologic uncertainty and the role of design rainfall in probabilistic flood maps, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-19385,, 2020.

EGU2020-20084 | Displays | NH1.1

Flood risk assessment and cultural heritage impact in the Instituto Superior de Arte (ISA) in Habana.

Daniele Fabrizio Bignami, Leonardo Stucchi, Daniele Bocchiola, Christian Zecchin, Davide Del Curto, Andrea Garzulino, and Renzo Rosso

Keeping ISA Modern is a project of Fondazione Politecnico di Milano and other partners aimed at planning the conservation of some of the buildings (Schools) of the University of Arts (ISA) of Cuba, built over a former country club, designed by eminent architects of the time (Vittorio Garatti, Roberto Gottardi and Ricardo Porro), and bestowed with the status of UNESCO World Heritage in 2003.

Most of the Schools are currently unusable, also due to damages caused by frequent floods from the surrounding Rio Quibù river, and they need urgent restoration if they are to be used. Personnel of Politecnico di Milano carried out a field survey on the Rio Quibù during 2019, and also based upon information from the Cuban National Institute of Hydraulic Resources (INRH) they studied established flood risk for ISA.

Here, we built a high-resolution digital terrain model (DTM) of the park where Schools are located, using laser scanner data, and previously georeferenced points. Using field measurements taken in June 2019 we were able to assess geometry (included bridges), slope and roughness coefficients of the main channel of the Quibù river, influence of the sea level. Then using as input critical discharge data provided by INRH we evaluated flood area and flood volume for 4 representative return periods (5, 20, 50, 100 years).

The most impacted building is the School of Ballet, located within a narrow meander of Rio Quibù, immediately upstream of a narrow bridge, clogging largely during floods, only 1 km far from the sea, and with drainage system unable to discharge storm water.

Given the high required cost, a partially collapsed wall originally partially protecting the School of Ballet was not rebuilt, and we are now exploring flood mitigation strategy which are cheaper, and feasible from the point of view of compatibility with the historical and architectural value of the building.

How to cite: Bignami, D. F., Stucchi, L., Bocchiola, D., Zecchin, C., Del Curto, D., Garzulino, A., and Rosso, R.: Flood risk assessment and cultural heritage impact in the Instituto Superior de Arte (ISA) in Habana., EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-20084,, 2020.

EGU2020-20797 | Displays | NH1.1

Innovative tools for improving flood risk reduction strategies: the FLORIS project

Giuseppe Tito Aronica, Giusina Brigandi, Negin Binesh, Simon McCarthy, Christophe Viavattene, Sally Priest, Emina Hadzcic, Miranda Deda, Laura Rossello, and Halim Koxhai

The FLORIS project aims to study innovative approaches for the development of integrated flood risk scenarios taking into consideration critical specific issues of areas at risk and the consequences of high frequency/low damage events that affect them. High frequency floods still involve and require mitigation actions on the part of civil protection and citizens before floodwaters inundate the land and directly impact assets. These emergency actions can benefit from enhanced protocol development based on realistic scenarios.

In particular, the main idea is to develop a supporting decision tool for the comparative analysis of disaster reduction strategies in flood risk management. This will have a specific focus on studying the functional vulnerability of critical infrastructure in order to preserve their efficiency during and after hazardous events. This include, hydraulic modelling at a finer scale, vulnerability and damage analysis at single element scale.

To address the project aims, identification of critical infrastructures that influences both the actions and outcomes of civil protection in flood prone areas and the disruption to the at-risk public, will be undertaken. To achieve the goal, initial steps consist of presenting to, and discussing with, civil protection teams the established approaches already available to them together with those identified by the project team from past research and within the literature. This will identify opportunities to further develop the civil protection protocols via innovative modelling of cascade effects incorporating existing algorithms. The developed procedures for flood risk reduction, taking into account resource management requirements will then be applied in a pilot case study, in the city of Berat, Albania and in Sarajevo, Bosnia and Herzegovina.

Working with the relevant professionals who are the principal beneficiaries of the project enables protocols to be co-developed to include associated physical, social and resource characteristics particular to the selected location. The main achievements will include enhanced management for flood protection in the beneficiary organisation with increased awareness of the interrelationships both spatially and temporally enhancing management protocols, protocols more closely aligned with existing beneficiaries’ procedures and resources for sustainability and establishing tools that are transferable to other regional and country contexts.

The main expected output is a suite of tools, embedded in a cascade procedure, able to support various actors (Civil Protection, municipalities, administrations, professionals, etc.) in planning and design measures to improve flood risk management actions under different and variable risk scenarios including climate and global change.


FLORIS (Innovative tools for improving FLood risk reductiOn stRategIeS) project has received funding from the EUROPEAN COMMISSION - under the 2018 Call Prevention and Preparedness in Civil Protection  (Project number: UCPM-2018-PP-AG  - 826561)

How to cite: Aronica, G. T., Brigandi, G., Binesh, N., McCarthy, S., Viavattene, C., Priest, S., Hadzcic, E., Deda, M., Rossello, L., and Koxhai, H.: Innovative tools for improving flood risk reduction strategies: the FLORIS project, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-20797,, 2020.

EGU2020-20508 | Displays | NH1.1

Flood proofing measures cost-efficiency analysis for hydraulic risk mitigation in an urbanized riverine area

Ugo Ventimiglia, Giuseppe Tito Aronica, and Angela Candela

Flood proofing measures cost-efficiency analysis for hydraulic risk mitigation in an urbanized riverine area

Ugo Ventimiglia 2, Angela Candela 1, Giuseppe Tito Aronica 2

1 Department of Engineering, University of Palermo, Palermo, Italy

2 Department of Engineering, University of Messina, Messina, Italy

Use of non-structural measures for flood risk mitigation is often more economically accessible, easy to implement and are highly effective, but only if this use is supported by a detailed hydraulic analysis necessary for a correct design. Among the non-structural measures, a progressive and increasingly accentuated importance is attributed to flood proofing interventions, especially in view of the pursuit of risk resilience objectives. Flood proofing interventions are normally classified in two main types: dry flood proofing and wet flood proofing. One measure of dry flood proofing is the shielding, which consists in the use of flood barriers, which can be installed at the entrance of the buildings or at a certain distance from them in order to avoid contact with the houses and deviate the flow of water. A similar type of interventions also avoids inducing sensations of false security (levee effect) in the exposed population and therefore contributes to increasing their resilience. In the context of risk management, resilience is the intrinsic ability of a system to modify its functioning before, during and following a change or an event, so as to be able to continue the necessary operations both under expected conditions and under unexpected conditions. Aim of work presented here is to determine an optimal combination and choice between different types of structural and non-structural measures, through the development of a methodology for assessing the real effectiveness of different measures, through a cost-benefit analysis (CBA) starting from the estimate of direct flood damage. The application of the CBA, to the real case study of the Mela river, located in north-eastern Sicily, which suffered a flooding in October 2015, supported by the determination of the real damages after the flood and the modelling of the same for the alternative scenario, has returned results significant capable of affirming the ability to reduce or avoid part of the damage.


How to cite: Ventimiglia, U., Aronica, G. T., and Candela, A.: Flood proofing measures cost-efficiency analysis for hydraulic risk mitigation in an urbanized riverine area, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-20508,, 2020.

EGU2020-20984 | Displays | NH1.1

Scaling the piping process

Willem-Jan Dirkx, Rens Van Beek, and Marc Bierkens

Scaling the piping process


W.J. Dirkx*a, L.P.H. van Beeka, M.F.P. Bierkensa,b


*Corresponding author

a University of Utrecht, Department  of Physical Geography, Faculty of Geosciences, P.O. 80.115, 3508 TC,    

  Utrecht, the Netherlands

bDepartmentStochastic hydrology and geohydrology, Deltares, P.O. 85467, 3508 AL, Utrecht, the Netherlands.


Seepage underneath river embankments during high water events can lead to erosion by piping. Elevated hydraulic gradients will drive groundwater flow, which when large enough, may breach the confining layer by bursting and wash out finer non-cohesive sediments, especially if the outflow is concentrated in a single point. As material is removed, a pipe may form and continue to progress upstream eventually undermining the embankment. Although often approached as a geotechnical or engineering problem in terms of embankment failure, the process can also be approached from different scales as a geohydrological problem. On the scale of an entire delta there are multiple channel belts that define the regional groundwater flow patterns. On the scale of a single stretch of river embankment the interaction between the river, present channel belts, their orientation, and channel belt architectural elements dominate the exact location of bursting and associated discharge. From there on the process scale becomes important, where the grain size distribution within the facies where the piping is taking place. And the process is dominated by regional bulk hydraulic conductivity in terms of discharge magnitude and grain size distribution at the tip of the pipe in terms of erodibility. In this study, a set of embedded models for the various scales is developed and tested that simulates the formation of a single pipe at these various scales in a holistic approach. Geohydrological conditions are linked to a representation of saturated hydraulic conductivity based on the local grain size distribution to model the feedback between groundwater flow, subsurface conditions and piping at these various scales. Thus, the model assesses the influence of subsurface heterogeneity on piping and its performance was assessed on the basis of field observations and laboratory experiments. Our results show the validity of the model and stress the need to treat piping as a three-dimensional geohydrological problem.

How to cite: Dirkx, W.-J., Van Beek, R., and Bierkens, M.: Scaling the piping process, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-20984,, 2020.

EGU2020-21969 | Displays | NH1.1

A data-driven statistical approach for flood hazard zoning at national scale

Ivan Marchesini, Mauro Rossi, Paola Salvati, Marco Donnini, Simone Sterlacchini, and Fausto Guzzetti

The delimitation of flood-prone areas is an important non-structural measure that proves to be effective in the long term in reducing food risk.

In Italy, more than 20 basin’s Units of Management (UoMs) were in charge to delineate the flood hazard zoning (FHZ) for three different flood return periods. Mostly, FHZ was prepared using physically based models i.e., considering the rainfall-runoff transformation and simulating the flood discharge through the river network. Physically-based models require many inputs and boundary conditions including: hydro-meteorological data, detailed characterization of the geometry of the riverbeds, roughness, infiltration parameters and also real hydrometric measurements in order to be calibrated. Physically based modelling is therefore a long, time consuming and resource intensive process that should be frequently updated to take into account the river channel changes. As a consequence, the Italian FHZ suffers from an underlying lack of homogeneity across the different UoMs, resulting in significant differences on the percentage of the river network for which the flood-prone areas were delineated.

As alternatives to physically based models, in recent years many authors have produced maps of flood susceptibility or hazard using expert (e.g. Analytic Hierarchy Process) or data-driven (e.g.  multivariate statistics or machine learning) approaches. Such methods were mostly used in ungauged territories where hydro-meteorological data is not available.

Here we present a procedure, named Flood-SHE (Flood - Statistical Hazard Evaluation), which is aimed at the delineation of flood-prone areas and the corresponding expected water depth, using a multivariate statistical classification model. Flood-SHE was applied to the entire Italian territory with the aim to integrate the UOMs FHZ where it is not available or incomplete. The classification model was trained exploiting the existing UoMs FHZ and using, as independent variables, a set of geomorphometric layers (derived at 10x10 meters ground resolution) which includes the distance and height to the closest rivers and to the basins outlets, the local DEM slope, a stream order classification criterion and the DEM local roughness. Random training and validation areas were used for the classification model in order to obtain an estimation of the uncertainty of the values of the predictive performance indexes. Results highlight (i) the significance of the the variables distance and height to the closest rivers, roughness and stream order in predicting the flood-prone areas, (ii) the impact of the UoMs morphology and the quality of UoMs FHZ on the reliability of the statistically modeled flood-prone areas.

How to cite: Marchesini, I., Rossi, M., Salvati, P., Donnini, M., Sterlacchini, S., and Guzzetti, F.: A data-driven statistical approach for flood hazard zoning at national scale, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-21969,, 2020.

EGU2020-22470 | Displays | NH1.1

FLOOD SUSCEPTIBILITY in ENDORHEIC AREAS: The case study of Salento peninsula in Apulia (Italy)

Michele Del Vecchio, Sara Brizzi, Carlo De Michele, Giovanni Menduni, and Maria Antonia Pedone

The concept of “flood susceptibility” is generally used to identify the flood prone areas. The flood susceptibility defines the probability of a territory to be flooded, and generally is determined according to its geo-litho-morphological and climatic characteristics. Here, we assessed the flood susceptibility in the Apulia region (Southern Italy). This region is characterized by the presence of endorheic basins located in the Salento peninsula. During ordinary rainfall events, these endorheic basins collect all the runoff into karst sinkholes. On the contrary, during severe rainfall events, the runoff saturates the capacity of sinkholes and the further runoff overflows in the lowland. The aim of the work is to characterize properly the flood susceptibility in endorheic areas, which is not adequately investigated at our knowledge.

How to cite: Del Vecchio, M., Brizzi, S., De Michele, C., Menduni, G., and Pedone, M. A.: FLOOD SUSCEPTIBILITY in ENDORHEIC AREAS: The case study of Salento peninsula in Apulia (Italy), EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-22470,, 2020.

EGU2020-22471 | Displays | NH1.1

Physically based metrics to evaluate the hydraulic distance between the drainage network and a DEM cell

Giovanni Menduni, Daniele Bignami, Carlo De Michele, Michele Del Vecchio, and Aravind Harikumar

The distance between the drainage network and a generic pixel of a DEM is an important indicator for different categories of geomorphologic and hydrologic processes, particularly as far as the analysis of susceptibility to flood is concerned (Tehrany, Pradhan, & Jebur, 2014). 

On the DEM domain D ⊂ ℜ3 and its subset given by the hydraulic network N ⊂ D, the distance is a function d: N x D → ℜ. The problem is far from uniquely determined, particularly in the field of flood susceptibility. In this specific case literature tends to consider two different distances, horizontal and vertical, given in theory by the projection of the actual distance on the two directions. Presently, the problem is effectively divided into substantially disconnected approaches.

Several authors, for the horizontal distance, use forms of Euclidean distance. Generally (Tehrany, Pradhan, & Jebur, 2014), (Tehrany, et al., 2017), (Lee, Kang, & Jeon, 2012), (Tehrany, Lee, Pradhan, Jebur, & Lee, 2014), (Khosravi, et al., 2018), (Rahmati, Pourghasemi, & Zeinivand, 2016) the distance is discretized in classes via buffers of progressively increasing size. The vertical distance, on the other hand, is determined as the absolute difference between the elevations. A different approach is taken from (Samela, et al., 2015), (Manfreda, et al., 2015), (Manfreda, Samela, Sole, & Fiorentino, 2014), (Samela, Troy, & Manfreda, 2017), who consider the flow distance, viz. the distance along the hydraulic path. This procedure firstly identifies for each point of DEM the nearest downstream element of the drainage network, and then calculates the difference between the corresponding elevations.

The flow distance well describes processes driven by gravity. Flood processes do not fall into these cases being governed by the hydraulic head difference between the river and the adjacent territory (the flow generally occurs with an adverse elevation gradient). Thus, the flooding will not follow classic direct runoff paths. For this, in order to quantify properly the distance (hereafter denominated “hydraulic distance”) between the drainage network and a DEM cell, an original model is introduced in which a flood process is simulated with a simple 2D unsteady flow parabolic model according to (Bates & De Roo, 2000) and implemented via a cellular automaton scheme. For each pixel of DEM, firstly we have determined the closest upstream pixel of the drainage network, and then the vertical distance as the difference of the two elevations. 

The model allows to improve the flood susceptibility of the territory. Results, generated on a huge number of DEMs, are quite encouraging. Developments are in progress to decrease computational time and memory storage size.

How to cite: Menduni, G., Bignami, D., De Michele, C., Del Vecchio, M., and Harikumar, A.: Physically based metrics to evaluate the hydraulic distance between the drainage network and a DEM cell, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-22471,, 2020.

NH1.2 – Innovative Techniques for Flood Assessment and Flood Risk Management

EGU2020-20446 | Displays | NH1.2 | Highlight

Probabilistic flood loss estimation for residential buildings in Europe

Max Steinhausen, Kai Schröter, Stefan Lüdtke, and Heidi Kreibich

Floods are the most costly natural disasters for European economies and expected to increase in frequency and magnitude within a changing climate. Governmental agencies, as well as the (re-)insurance sector, rely on accurate flood loss estimations on the European scale to support climate change adaptation policies, prepare for economic impacts, for instance, via the EU solidarity fund and calculate premiums.

Flood loss estimation on the European scale is currently based on deterministic depth-damage functions different for each country. This leads to a fragmented approach in flood loss estimation, greatly simplifying the representation of damage processes without information about associated uncertainties. To overcome these shortcomings we developed the Bayesian Network Flood Loss Estimation MOdel for the private sector (BN-FLEMOps). BN-FLEMOps estimates relative loss to residential buildings depending on flood experience of the population, precautionary measures, building area, building type, return period, duration and water depth (Wagenaar et al. 2018). The structure of this probabilistic multi-variable model is based on empirical data from post-flood surveys and uses consistent continent-wide proxy data for European scale application. BN-FLEMOps was successfully validated in three case studies in Italy, Austria and Germany. The officially reported loss figures of the past flood events were within the 95% quantile range of the probabilistic loss estimation (Lüdtke et al. 2019).

The probabilistic approach enables the quantification of uncertainties of the loss estimates. Model outputs are generated as loss distributions in high spatial resolution, offering Europe-wide information about risk and uncertainty. Thus, providing support for decision-making processes in flood risk management.

Easy applicability to the BN-FLEMOps model is ensured by its implementation in the standardized OASIS loss modeling framework (lmf). The OASIS lmf enables a plug and play combination with various input data sets and other models.

A first application of BN-FLEMOps for a Europe-wide 100 years flood hazard scenario provided by the Joint Research Center resulted in accumulated loss for residential buildings in Europe of 79.0 billion euro (Q20 = 32.3; Q80 = 213.8).



Lüdtke, S., Schröter, K., Steinhausen, M., Weise, L., Figueiredo, R., Kreibich, H. (2019 online first): A consistent approach for probabilistic residential flood loss modeling in Europe. - Water Resources Research. DOI:

Wagenaar, D., Lüdtke, S., Schröter, K., Bouwer, L. M., Kreibich, H. (2018): Regional and Temporal Transferability of Multivariable Flood Damage Models. - Water Resources Research, 54, 5, pp. 3688-3703. DOI:

How to cite: Steinhausen, M., Schröter, K., Lüdtke, S., and Kreibich, H.: Probabilistic flood loss estimation for residential buildings in Europe, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-20446,, 2020.

EGU2020-19760 | Displays | NH1.2

Fluvial flooding hazard assessment in Northern Italy: potential and informativeness of different geomorphic classifiers

Attilio Castellarin, Simone Persiano, Caterina Samela, Andrea Magnini, Stefano Bagli, Paolo Mazzoli, and Valerio Luzzi

The steady increase of economic losses and social consequences caused by flood events in Europe, as a result of the combined effects of anthropization (e.g. land-use and land-cover changes) and climate change, calls for updated and efficient technologies for assessing pluvial, fluvial and coastal flood hazards and risks. In this context, the EIT-Climate KIC SaferPLACES () project aims at exploring and developing innovative and simplified modelling techniques to assess and map flood hazard and risk in urban environments under current and future climates. Concerning fluvial flooding, detailed inundation maps can be accurately obtained by means of hydrological and hydraulic numerical models, whose application, though, is often very resource intensive. For this reason, consistent and harmonized national flood hazard maps are still lacking in many countries of the world. Several studies have proved that flood-prone areas can be delineated by considering linear binary geomorphic classifiers, which are computed by analysing Digital Elevation Models, DEMs, and whose threshold values are calibrated relative to existing hydraulic flood hazard maps. One of these indices, the so-called Geomorphic Flood Index (GFI), was recently shown to be cost-effective, reliable and efficient for identifying flood-prone areas in several test sites in the United States, Africa and Europe. As part of the activities of SaferPLACES, in this study we test different geomorphic classifiers (GFI included) for the identification of flood-prone areas in a wide area in Northern Italy (c.a. 100000 km2, including Po, Adige, Brenta-Bacchiglione and Reno river basins). We refer to the recently compiled MERIT (Multi-Error-Removed Improved-Terrain) DEM, a 3sec-resolution (~90m at the equator) DEM developed by removing multiple error components from existing spaceborne DEMs. As reference maps for the calibration, we select the flood hazard maps provided by (i) the Italian Institute for Environmental Protection and Research (ISPRA), and (ii) the Joint Research Center (JRC) of the European Commission. Our study confirms the better performances of GFI compared to other geomorphic classifiers, also providing useful information regarding the sensitivity of GFI threshold values relative to different reference hazard maps; it also suggests as a promising avenue for future researches the combination of multiple geomorphic indices through data-driven approaches and artificial intelligence.

How to cite: Castellarin, A., Persiano, S., Samela, C., Magnini, A., Bagli, S., Mazzoli, P., and Luzzi, V.: Fluvial flooding hazard assessment in Northern Italy: potential and informativeness of different geomorphic classifiers, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-19760,, 2020.

EGU2020-10285 | Displays | NH1.2 | Highlight

Towards the Development of a High-resolution, Global Streamflow and Flood Forecasting System – An U.S. Interagency Collaboration Effort

Sudershan Gangrade, Mario Morales-Hernandez, Ahmad A. Tavakoly, Kristi R. Arsenault, Jerry Wegiel, Kimberly McCormack, Mark Wahl, Sujay V. Kumar, Christa D. Peters-Lidard, Shih-Chieh Kao, and Katherine J. Evans

This work provides an envisioned overview of scientific collaboration among multiple United States agencies including the National Aeronautics and Space Administration (NASA), U.S. Army Engineer Research and Development Center (ERDC), Oak Ridge National Laboratory (ORNL), and National Geospatial-Intelligence Agency (NGA) for the integration of existing data and model capabilities to support global scale water security applications. The primary objective is to develop a high-resolution, operational streamflow and flood forecasting system at the global scale, leveraging multiple process-based models, remote sensing data assimilation, and high-performance computing techniques. We present a preliminary case study that demonstrates the integration of the modeling framework using NASA’s Land Information System (LIS), ERDC’s Streamflow Prediction Tool (SPT), and ORNL’s GPU-accelerated 2D flood model (TRITON). Using the high-resolution terrain data from NGA, a historic flood event that occurred in March 2019 at Offutt Air Force Base in Nebraska, USA, was simulated on ORNL’s supercomputer, Summit. This benchmark test case is used to validate the modeling framework and to help establish a roadmap for the expanded modeling efforts at the global scale. In a broader sense, the proposed infrastructure will enable decision-makers to address issues such as transboundary water conflicts, flood and drought monitoring, and sustainable water resources management and to study their impacts on human, water-energy and natural systems in the short, medium and long term.

How to cite: Gangrade, S., Morales-Hernandez, M., Tavakoly, A. A., Arsenault, K. R., Wegiel, J., McCormack, K., Wahl, M., Kumar, S. V., Peters-Lidard, C. D., Kao, S.-C., and Evans, K. J.: Towards the Development of a High-resolution, Global Streamflow and Flood Forecasting System – An U.S. Interagency Collaboration Effort, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-10285,, 2020.

Glacial lake outburst floods (GLOFs) are one of the major natural hazards in certain populated mountainous areas, e.g. the Himalayan region, which may lead to catastrophic consequences including fatalities. Evaluating the potential socio-economic impact of GLOFs is essential for mitigating the risk of GLOFs and enhancing community resilience. Yet in most of the cases, the impact evaluation of potential GLOFs is confronted with limited data availability and inaccessibility to most of the glacial lakes in the high-altitude areas. This study aims to exploit recent advances in Earth Observation (EO), open-source data from different sources, and high-performance hydrodynamic modelling to innovate an approach for GLOF risk and impact assessment. GLOF scenarios of different glacier dam breach width and depth are designed according to high-resolution aerial imagery and terrain data acquired from unmanned aerial vehicle surveying. High-performance hydrodynamic model supported by open-source multi-resolution data from the latest EO technologies is used to simulate the flood hydrodynamics to provide spatial and temporal flood characteristics. Detailed information on communities and infrastructure systems is collected and processed from multiple sources including OpenStreetMap, Google Earth, and global data products to support impact analysis. The evaluation framework is applied to Tsho Rolpa glacial lake in Nepal, which has been identified as one of the potentially dangerous glacial lakes that may create GLOFs to threaten the downstream communities and infrastructure. According to the simulation results, the worst GLOF scenario can potentially inundate 27 villages, 583 buildings and 20.8 km2 of agricultural areas, and pose high risk to 1 airport, 1 hydro power plant, 3 bus stations, and 21 bridges. Additionally, the spatial and temporal flood simulation results, including water depth, flow velocity and flood arrival time may help identify impacted sites and objects, which would be valuable for the development of evacuation plans and early warning systems.

How to cite: Chen, H., Liang, Q., Zhao, J., and Xia, X.: High-resolution glacial lake outburst flood impact evaluation using high-performance hydrodynamic modelling and open-source data, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-3714,, 2020.

EGU2020-21878 | Displays | NH1.2

Bayesian Networks for storm surge estimation in Mississippi (US)

Alvaro Prida, Manuel Andres Diaz Loaiza, Jeremy Bricker, Oswaldo Morales, Remy Meynadier, Trang Duong, Rosh Ranasinghe, and Arjen Luijendijk

Bayesian Networks for storm surge estimation in Mississippi (US)

A. Prida1, A. Diaz Loaiza1, J. Bricker1, R. Meynadier2, O. Morales-Napoles1, T. Duong3, R. Ranasinghe3, A. Luijendijk1

The unprecedented damage due to flood caused by hurricanes like Katrina (2005) has reinforced the interest of the hydraulic community to improve the storm surge estimation for the North Gulf of Mexico. Very high-resolution hydrodynamic models have been traditionally used for this end. However, these models are computationally very expensive. In this paper, a Bayesian Network (BN) is built to estimate storm surge at the coastal areas of Mississippi. A catalogue of HURDAT2 historical hurricanes is simulated in Delft3D FM to generate a surge data base that is used for the training of the Bayesian Network. The storm surge obtained from Delft3D FM is validated against observations recorded during a past historical event. The landfall location, the maximum wind speed, the forward speed and the forward direction of the hurricane at landfall are the other variables considered in the Bayesian Network. The Bayesian Network is validated by inferring values from past historical events in the model and comparing the modeled surge to observations.

How to cite: Prida, A., Diaz Loaiza, M. A., Bricker, J., Morales, O., Meynadier, R., Duong, T., Ranasinghe, R., and Luijendijk, A.: Bayesian Networks for storm surge estimation in Mississippi (US), EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-21878,, 2020.

EGU2020-18039 | Displays | NH1.2 | Highlight

Can performance metrics accounting for the flood extent shape improve inundation model calibration?

Thaine H. Assumpção, Ioana Popescu, Andreja Jonoski, and Dimitri P. Solomatine

The calibration and validation of inundation models have since long been influenced by data availability. When only stage hydrographs and high water level marks were available, metrics such as the Root Mean Square Error (RMSE) were selected for goodness-of-fit assessment. When remotely sensed flood extent data started to be obtained, binary performance measures started being used. Although data availability and modelling resolution have advanced in the past decades, the methods behind performance evaluation remain similar. Shape-based metrics used in topology and pattern recognition could enhance not only the raw model performance but our ability to diagnose achieved results. Therefore, in this study, we discuss how much improvement in calibration can be obtained by employing shape matching metrics. The research is conducted in two experiments: a 2D hydrodynamic benchmarking model and the Po River case study. Different metrics traditionally used in inundation modelling and metrics tailored towards shape matching were employed. Calibration of the Manning coefficient was performed using one metric at a time. Experiments showed that metrics incorporating scale components (e.g. differences in areas and/or distances) provide better calibration. This corroborates the wide use of traditional metrics and indicates the potential of using shape-based metrics, which can augment our ability to diagnose models and improve modelling results.

How to cite: Assumpção, T. H., Popescu, I., Jonoski, A., and Solomatine, D. P.: Can performance metrics accounting for the flood extent shape improve inundation model calibration?, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-18039,, 2020.

EGU2020-8932 | Displays | NH1.2

Towards deep learning based flood forecasting for ungauged basins

Frederik Kratzert, Daniel Klotz, Guy Shalev, Sella Nevo, Günter Klambauer, Grey Nearing, and Sepp Hochreiter

Floods are among the most destructive natural hazards in the world. To reduce flood induced damages and casualties, streamflow forecasts should be as accurate as possible.

As of today, streamflow forecasts are usually made with either conceptual or process-based hydrological models. The problem these models usually have is that they perform best when calibrated for a specific basin, and performance degrades drastically if the models are used in places without historic streamflow measurements. To make things worse, some of the most devastating floods occur in developing and low-income countries, where historic records of streamflow measurements are scarce. Therefore, a central task for enhancing flood forecasts and helping local authorities to manage these areas is to provide high-quality streamflow forecasts in ungauged rivers. Although the IAHS dedicated an entire decade (2003-2012) to advance the problem of Prediction in Ungauged Basins the central goal remains largely a challenge.

In this talk, we will present a novel approach for tackling the problem of prediction in ungauged basins using a data-driven approach. More concretely, we show that the Long Short-Term Memory network (LSTM), which is a special type of a deep learning model, can serve as a generalizable rainfall-runoff simulation model. We will present recent results indicating that the LSTM gives on average better out-of-sample predictions (ungauged prediction) than e.g. the SAC-SMA in-sample (gauged) or the US National Water Model (Kratzert et al., 2019).

One place where these research results are already finding their way into operation is Google’s Flood Forecasting Initiative. The goal of this initiative is to provide (enhanced) flood warnings, where needed, starting with a pilot project in India. And as mentioned above, historic streamflow records in those regions are scarce, which motivates new and innovative approaches for enhanced streamflow forecasting.


Kratzert, F., Klotz, D., Herrnegger, M., Sampson, A. K., Hochreiter, S., & Nearing, G. S.: Toward improved predictions in ungauged basins: Exploiting the power of machine learning. Water Resources Research, 55., 2019.

How to cite: Kratzert, F., Klotz, D., Shalev, G., Nevo, S., Klambauer, G., Nearing, G., and Hochreiter, S.: Towards deep learning based flood forecasting for ungauged basins, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-8932,, 2020.

EGU2020-2086 | Displays | NH1.2

Implement of JW ecological technology to an area under heavy rainfall

Hund-Der Yeh, Kuo-Chen Ma, Tze-Y Chan, and Mo-Hsiung Chuang

Floods and droughts are exacerbated due to global warming and climate change. Heavy rainfall often leads to serious flooding events. How to improve traditional methods for storm sewer system design or alternative measures therefore has become an important issue in Taiwan. The objective of this study is to use the SWMM module to simulate the use of the JW eco-technology (JWET) in an area under different heavy rainfall resulting in surface runoff and infiltration. A small region in a city in north Taiwan is selected as the target area for the simulations and the results are compared with the flood potential map produced based on the simulation results from the SOBEK model developed by Deltares System for river, urban or rural management. The low-impact development module of the SWMM is chosen to simulate the spatial distributions of surface runoff and infiltration using the JWET in the target area under different heavy rainfall intensities. The results show that the implement of JWET to the target area can effectively reduce surface runoff and significantly increase surface infiltration and groundwater recharge. In other words, the implement of JWET to an urban area can achieve the objective of environmental adaptation and reduce the loss of people's lives and property.


Keywords: heavy rainfall; low impact development; JW ecological technology

How to cite: Yeh, H.-D., Ma, K.-C., Chan, T.-Y., and Chuang, M.-H.: Implement of JW ecological technology to an area under heavy rainfall, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-2086,, 2020.

EGU2020-3828 | Displays | NH1.2

1D flow simulation with irregular cross-sections using the pre-balanced shallow water equations

Shangzhi Chen, Feifei Zheng, and Qingzhou Zhang

With the possible climate change and increased pace of urbanization in the century, urban flooding has caused more and more attentions nowadays. Shallow water equations are widely used to reproduce the flow hydrodynamics of flooding around the urban areas, which have been proved a powerful tool for flood risk assessment and evacuation management, like river flow or flowing at drainage networks with irregular cross-sections at 1D scale. Over the last two decades, Godunov-type schemes have became popular for its robustness treating complex flow phenomenons. When tacking complex topography in the framework of Godunov-type scheme, sourer term needs to be treated property to preserve steady state, that flux gradient and sourer term are balanced. Capart et al. (2003) reconstructed the momentum flux by considering the balance of hydrostatic pressure with the approximated water surface level, which has the ability to tackle the irregular and non-prismatic channel flow with complex topography. This approximation is exact for two cases: 1) rectangular and prismatic channel; 2) water surface is horizontal. However, for other cases, approximation is employed to achieve the hydrostatic equilibrium, which has reduced the accuracy of the numerical solution and increased the complexity for the model implementation. 

In this work, we present a new well-balanced numerical scheme for simulating 1D frictional shallow water flow with irregular cross-sections over complex topography involving wetting and drying. The proposed scheme solves, in a finite volume Godunov-type framework, a set of pre-balanced shallow water equations derived by considering pressure balancing (Liang and Marche, 2009). HLL approximated Riemann solver is adopted for the flux calculation at the cell interface. Non-negative reconstruction of Riemann state (Audusse et al., 2004) and local bed modification (Liang, 2010) produce stable and well-balanced solutions to shallow water flow hydrodynamics. Bed slope source term can be approximated using central difference and no special treatment is needed for wet and dry bed. The friction source term is discretized using a splitting implicit scheme and limiting value of friction force is used to ensure stability for the dry bottom (Liang and Marche, 2009). The new numerical scheme is validated against two theoretical benchmark tests and then compared with the validated shallow water model with circular and trapezoid cross-sections over complex topography involving wetting and drying. This method is also possible to reproduce the mixed flow in the conduit or for the flow with non-prismatic channel like river flow in the near future.


Audusse, E., Bouchut, F., Bristeau, M. O., Klein, R., & Perthame, B. T. (2004). A fast and stable well-balanced scheme with hydrostatic reconstruction for shallow water flows. SIAM Journal on Scientific Computing, 25(6), 2050-2065.

Capart, H, Eldho, TI, Huang, SY, Young, DL, and Zech, Yves, "Treatment of natural geometry in finite volume river flow computations", Journal of Hydraulic Engineering 129, 5 (2003), pp. 385--393.

Liang, Qiuhua and Marche, Fabien, "Numerical resolution of well-balanced shallow water equations with complex source terms", Advances in water resources 32, 6 (2009), pp. 873--884.

Liang, Qiuhua, "Flood simulation using a well-balanced shallow flow model", Journal of hydraulic engineering 136, 9 (2010), pp. 669--675.

How to cite: Chen, S., Zheng, F., and Zhang, Q.: 1D flow simulation with irregular cross-sections using the pre-balanced shallow water equations, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-3828,, 2020.

EGU2020-21120 | Displays | NH1.2

1-D Dam-Break Modeling: Case Study of Successive Dam-Break

Byunghyun Kim, Hyun Il Kim, and Kun Yeun Han

Unexpected disastrous floods or flash floods caused by climate change are becoming more frequent. Therefore, there is a possibility of dam failure due to natural disasters including heavy rainfall, landslide and earthquakes, and an unexpected emergencies may be caused by the defect of dams or appurtenant structures due to the aging of the dam. It is desirable to prevent in advance because emergencies such as dam failure can cause many casualties and property damage.

Dam failure rapidly propagates enormous flow to the downstream, so the evacuation time is short and causes many casualties compared to other types of floods. In order to minimize casualties from dam failure, it is important to establish emergency action plan, flood hazard map and advance warning system. For the establishment of these three, accurate dam failure modeling is required. Most of the studies on dam failure modeling have been conducted for single dam failure rather than successive failure of two or more dams. This study conducted a successive failure modeling of Janghyun Dam and Dongmak Dam in Korea, which collapsed due to Typhoon Rusa in 2002.

The DAMBRK (Dam-Break Flood Forecasting Model) has been applied to the successive failure modeling of two dams which are located in parallel. The relaxation scheme was added to DAMBRK to consider the tributary cross-section. In addition, this study proposed a method to estimate the dam failure duration using empirical formulas for the peak discharge of dam failure and failure formation time of ASDSO (Association of State Dam Safety Officials). The failure hydrograph of two dams was estimated using the proposed method and the discharge and water surface elevation were predicted at the main locations of downstream according to the propagation of dam failure discharge. The accuracy and applicability of the modeling were validated by comparing the predicted water surface elevations with field surveyed data and showing good agreements between predictions and measurements.

Keywords:  Successive Dam-Break, Flooding, DAMBRK


This work was supported by Korea Environment Industry & Technology Institute(KEITI) though Water Management Research Program, funded by Korea Ministry of Environment(MOE)(79609)

How to cite: Kim, B., Kim, H. I., and Han, K. Y.: 1-D Dam-Break Modeling: Case Study of Successive Dam-Break, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-21120,, 2020.

EGU2020-5448 | Displays | NH1.2

High-resolution DEM Creation using a UAV for Flood Inundation Hydrodynamic Modeling- A Case of Rel River Flood, Gujarat, India

Dhruvesh Patel, Raviraj Dave, Amit Kumar Dubey, Praveen Kumar Gupta, and Raghavendra Singh

Catastrophic flood leads to a major disaster in developing countries. It loses a life and significant valuable properties, therefore it assessment is a prime requirement to identify the risk and vulnerable area in a flood-prone region. Many hydrodynamic models are providing a solution to identify the flood inundation area, flood arrival time, and velocity of flow in flood susceptible area, however, due to the low resolution of DEM, it can’t assess the actual flooding condition. To overcome this limitation, the present study describes the creation of high resolution (3 cm gridded) DEM for Dhanera city, Rel river catchment in Gujarat where it was affected by the catastrophic flood in the year of 2015 and 2017. Phantom 4 Pro RTK, DGPS and Pix4 software are used for creation of high-resolution DEM. The entire 10 km2 area of Dhanera city is divided 4 blocks and each block is mapped by Phantom 4 pro-RTK Unmanned Aerial Vehicle (UAV) at 80 % image overlaps. A total of 9222 images are captured and post-processed using a Pix 4 software. Ground Control Points were marked for rectification in the geo-location of aerial images using DGPS (RTK). The aerial images collected during the survey have a spatial resolution of 3 cm with geo-location. The data collected is put for post-processing using Pix4D mapper software. 3D classified point cloud, DTM and DSM of 3 cm spatial resolution, orthomosaic of 3 cm spatial resolution are produced after the processing. Generated High-resolution DEM (DTM & DSM) will be utilized for hydrodynamic modeling to produce a precise flood inundation maps. 


Acknowledgement: The corresponding author is thankful to the ORSP, PDPU, and SAC-ISRO, SARITA program for providing the research grant to execute the work. (Grant no: ORSP/R&D/SRP/2019/MPDP/007; SAC/EPSA/GHCAG/LHD/SARITA/01/19)

How to cite: Patel, D., Dave, R., Dubey, A. K., Gupta, P. K., and Singh, R.: High-resolution DEM Creation using a UAV for Flood Inundation Hydrodynamic Modeling- A Case of Rel River Flood, Gujarat, India, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-5448,, 2020.

EGU2020-11947 | Displays | NH1.2

Review of city models and the applications on flood risk management

Yiheng Chen, Lu Zhuo, and Dawei Han

Cities are the place where a large portion of the population lives. Traditional urban planning models usually based on separate functions of a city or region. A coherent city model is a newly developed tool to take the interaction between each section into consideration. The city model in this paper focuses on the water system infrastructure because flood risk is becoming an increasingly challenging issue with the rapid urbanization and extreme weather under climate change. The paper aims to give a timely review of the development of city models from various originates. Then, it introduces a number of popular modelling techniques that have been demonstrated useful or may be of potential usage for city modelling purpose, such as GIS, CIM, ABM, etc. The review of model techniques provides the readers with suggestions on how to choose the technique to deal with their own research question. After that, this paper also points out the possible future directions of city models with challenges requiring further research efforts.

How to cite: Chen, Y., Zhuo, L., and Han, D.: Review of city models and the applications on flood risk management, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-11947,, 2020.

This research is part of the ongoing research project Climate Change Adaptation to ManagE the Risks of Extreme HydrologicaL and Weather Events for Food Security in Vulnerable West Nile Delta (CAMEL). The study area−West Nile Delta−is an important region in Egypt in terms of agricultural and industrial productions, whilst it is a vulnerable area facing extreme weather and environmental crises (e.g. flooding, soil salinization, and sea level rise), as well as in socio-economic respect. In the latest decades, the region suffered more weather extremes due to climate change; the severe rainfall events resulted in flooding causing heavy casualties and economic loss. Therefore, the project aims to build an integrated flood early warning system for Egypt. However, in order to tackle the issue of data scarcity of ground observation, this research seeks to apply satellite precipitation observation and numerical weather prediction (NWP) as the substitution (i.e. GPM, MPE and ECMWF data) and to develop an approach with the integration of Nowcasting and NWP for precipitation forecasting.

Generally known that Nowcasting method and NWP both have limitations in performing local convective and formative precipitations, whilst in different reasons. The research seeks to improve this effect in Nowcasting as it has advantage in short term performance (i.e. a few hours) whilst NWP has advantage in long term performance (i.e. a few days). The findings from the vector field of Nowcasting indicate that the relativity between shift speed and shape changing speed of precipitation is the key for accurate prediction, which is the disadvantage of the optical flow approach of the Lagrangian method that Nowcasting applies as the main stream core. The research hence applies a machine learning approach−support vector machine (SVM)−to figure out the relativity aforementioned to identify disadvantage data that needs to be pre-treated prior to the Lagrangian Nowcasting. Meanwhile, by applying a phase-based frame interpolation method based on the Eulerian method to downscale the temporal resolution, it can improve these disadvantage data identified by machine learning so as to better perform in the Lagrangian Nowcasting. The integrated Nowcasting approach is expected to have better performance in forecasting and still retains low computational resource consumption.

How to cite: Chen, C.-N., Rico-Ramirez, M., Han, D., and Abdelhalim, A.: An Integrated Nowcasting Approach with Machine Learning for Applying Global Sensing Datasets to Forecast Precipitation Extremes in Data-scarce Nile Delta, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-11380,, 2020.

EGU2020-4251 | Displays | NH1.2

Simulation of Floating Debris during a Flash Flood Event

Liang Qiuhua, Yan Xiong, and Gang Wang

Under climate change, extreme weather events such as storms and intense rainfall has become far more frequent. This is evidenced by the outburst of multiple flood events in the recent years in the UK and other parts of the world. Induced by intense rainfall, flash flooding is one type of wide-spread natural hazards that can pose serious threats to people’s lives and properties. Most likely happening in steep rapid-response catchments following localized high intensity rainfall, flash floods are characterized by rapid rise of water level and high flow velocities in channels and floodplains. The violent flood waves can remove and transport heavy objects such as cars and tree, imposing extra risk to people and infrastructure, e.g. bridges.

On 16th August 2004, the coastal village of Boscastle in north Cornwall, UK, was devastated by a flash flood following an exceptional amount of rain that fell over eight hours. The village suffered extensive damage and notably, some 100 vehicles were washed to downstream and into the sea, some of which blocked bridges and altered flood hydraulics. This work aims to reproduce the flood event including floating debris dynamics using a new coupled hydrodynamic model. The coupled modelling tool predicts the flooding process using a finite volume shock-capturing model that solves the fully 2D shallow water equations (SWEs), which is coupled with a discrete element model (DEM) to simulate the interactive dynamics of floating objects. The coupled model is further accelerated by implementation on modern GPUs and is therefore well-suited for simulation of large-scale transient flood hydrodynamics enriched with floating debris. The simulation results are first confirmed by comparing with maximum flood depths collected after the event. Further simulations are carried out to investigate the influence of floating vehicles on flood hydrodynamics and understand how they block bridges and alter flood paths. The simulation results are consistent with observations captured during the event.

Key Words: Flash flooding; Hydrodynamic model; Shallow water equations; Discrete element model; Floating debris

How to cite: Qiuhua, L., Xiong, Y., and Wang, G.: Simulation of Floating Debris during a Flash Flood Event, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-4251,, 2020.

EGU2020-11512 | Displays | NH1.2

Variability assessment of flood hazard indicators on the North Caucasus

Anastasiia Mironenko, Ekaterina Rets, and Natalia Frolova

The result of maximum water levels variability analysis along with the information of the frequency of adverse and dangerous hydrological phenomena exceeding levels and fluctuations maximum amplitude of water levels are presented in this research. There are two periods of comparison of the water levels recorded at 146 hydrological gauges – 1926-1975 and 1976-2015. Statistical analysis of databases was selected as the main research method including agreement criteria with parametric and nonparametric criteria of homogeneity.

The recent rise in mathematical expectation of maximum water levels is a characteristic for all the North Caucasian rivers. Maximum water levels dispersion have a tendency to decrease in the south of the Black Sea Caucasian coast, the Psheha and the Belaya rivers, the Sulak and the Fortanga rivers, the Baksan upstream. The remaining gauges recorded an increase in water levels dispersion, which is the predominant trend for the North Caucasian rivers.

The frequency of the adverse events exceeding water levels reaches 50% on the Afips, the Belaya, the Kuma, the Laba, the Mzymta, the Ubinka and the Vulan rivers. By the number of hazard levels exceeded, the areas adjacent to the Kuma, the Laba, the Psekups, the Pshish and the Ubinka are most susceptible to the floods.

Another part of the framework was connected with potential flood-affected region mapping over the North Caucacus. Thus, a map of potential flood zones caused by North Caucasian rivers was created according to maximum water levels recorded at 232 hydrological gauges.

This study was funded by RFBR according to the research project № 20-35-70024.

How to cite: Mironenko, A., Rets, E., and Frolova, N.: Variability assessment of flood hazard indicators on the North Caucasus, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-11512,, 2020.

A considerable share of the losses by extreme flooding are in upstream areas, where centralized flood mitigation measures have no effect. Consequently, modern flood mitigation strategies address this problem by a distributed combination of measures, including nature-based solutions and decentralized flood detention basins. These small basins can be realized by minor changes in the landscape and can influence the runoff behavior at the site and downstream. However, the economic viability of the sites and the local and regional effectiveness depend on the location optimization, which is influenced by the local topography as well as by complex superposition effects.
We address this complexity with a combination of two innovative and automated optimization tools: LOCASIN (LOCation detection of retention and detention bASINs) is a flexible tool to automatically detect, characterize and evaluate detention basin locations. It is based on topographical data and provides information on the basin geometry as well as on the required curves for basin retention calculations. TOBAS (Tool for the Optimization of BASin efficiencies) calculates the effectiveness of a basin combination, taking into account the mutual influence when optimizing the throttle size. The input data includes the relation of water level and retention volume from LOCASIN and hydrographs generated by a hydrological model (e.g. WaSiM). Furthermore, TOBAS can be applied to select and dimension an optimized basin combination from the locations determined with LOCASIN. The optimization is based on the respective objective, e.g. effectiveness or economic efficiency. Hence, the joint application of both tools can contribute to improve efficient flood mitigation strategies and enhance flood resilience. The applicability of the tools and the benefits for the assessment of flood mitigation concepts were tested and confirmed by means of different Bavarian catchments.

How to cite: Teschemacher, S. and Disse, M.: Automated location optimization of detention basins as a contribution to an efficient flood mitigation strategy, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-18342,, 2020.

EGU2020-21349 | Displays | NH1.2

Piping in practice: Incorporating natural subsurface variability into backward erosion models

Tim Winkels, Willem Jan Dirkx, Kim Cohen, Hans Middelkoop, Rens van Beek, Marc Bierkens, and Esther Stouthamer

River embankments form an essential part of the primary flood defence in the Netherlands. Of all failure mechanisms, piping is considered one of the key mechanism for triggering dike destabilization of river dikes in Rhine-Meuse Delta. Within the STW project Piping in practice, we aim to better understand 1) the influence of variability within subsurface characteristics on the piping process, and 2) the natural variability of these subsurface characteristics underneath embankments in the Rhine-Meuse delta.  
We employ the lithogenesis of sandy deposits to group variability in subsurface parameters across different scales. Using extensive borehole datasets, we quantified regional trends within and between geological units in order to investigate geological controls on variability these subsurface properties. On a smaller scale, laboratory experiments have shown that larger variation in grain size or layering in porous media have a retarding effect on the progression of small-scale pipes, demonstrating the importance of incorporating these variabilities into the piping assessments.  Combining laboratory experiments and field observations, representative sedimentary architectures are implemented into digital piping models at several embedded scales. This will allow us to better describe subsurface variability in terms of model parameters, and improve computation of the piping process.

How to cite: Winkels, T., Dirkx, W. J., Cohen, K., Middelkoop, H., van Beek, R., Bierkens, M., and Stouthamer, E.: Piping in practice: Incorporating natural subsurface variability into backward erosion models, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-21349,, 2020.

EGU2020-4605 | Displays | NH1.2

GIS based Development of MCDM Model for Flood Risk Management across Godavari Lower Sub-Basin of India

B. Thanga Gurusamy, Avinash D Vasudeo, and Aniruddha Dattatraya Ghare

Abstract: Because of the uncertainty and high cost involved, the Absolute Flood Protection has not been considered as a rational decision. Hence the trend is to replace Absolute Flood Protection strategy by Flood Risk Management Strategy. This Paper focus on the development of Multiple Criteria Decision Making (MCDM) model towards Flood Risk Management (FRM) across Godavari Lower Sub-Basin of India using GIS based methodologies for Flood Hazard Zonation in order to achieve global minimum of the Flood predicted Risk level.  Flood Hazard Zone Map for the historical flood events obtained with the use of GIS based Digital Elevation Models across the study area have been presented and used for the estimation of Hazard Risk. Uncertainty (or Control) Risk levels of each Flood estimated using various Flood Forecasting methodologies have been compared for the selected locations of the study area. Effectiveness of Passive Flood Protection Measures in the form of Flood Levees has been quantitatively analyzed for the increase in the Opportunity Risk and corresponding reduction in the Flood Hazard Risk. Various types of Multi-Objective Evolutionary Algorithms (MOEAs) have been used  to determine a Compromise solution with conflicting criteria between Hazard Risk and Opportunity (or Investment) Risk and the results were compared for each of the selected levels of Flood estimated with corresponding uncertainty. Traditional optimization method in the form of Pareto-Optimal Front have also been graphically depicted for the minimization of both Hazard Risk Objective function and Opportunity Risk Objective Function and compared with those obtained using MOEAs. Watershed wise distribution of optimized Flood Risk variation across the Sub-basin has been presented graphically for both the cases of with and without active Flood Routing Measures. Keywords:  Flood Risk Management; GIS based Flood Hazard Zonation; Multi-Criteria Decision Making; Multi-Objective Evolutionary Algorithms; Godavari Lower Sub-Basin of India;

How to cite: Gurusamy, B. T., Vasudeo, A. D., and Ghare, A. D.: GIS based Development of MCDM Model for Flood Risk Management across Godavari Lower Sub-Basin of India, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-4605,, 2020.

EGU2020-2524 | Displays | NH1.2

Assessment of flood effect on semi-arid special investment region using 1D hydrodynamic modeling

Sanjay Yadav, Surendra Borana, Namrata Jariwala, and Shri Ram Chaurasia

The present study evaluates floods of semi-arid region with flat topography. The flood water spread over hundreds of square kilometer being delta region of Sukhbhadar River. The government of Gujarat aims to develop study region which spreads over 920 sq. km as Dholera Special Investment Region (DSIR). The study area is highly prone to flooding due to confluence of number of rivers namely Sukhbhadar, Lilka, Utavli and Padalio and tidal ingress from Gulf of Cambay.

Sukhbhadar River enters the DISR area near village Kashindra and flows through the Town Planning Scheme -TP1 and one of its tributaries Adhiya River, originating from village Cher flows through the Town Planning Scheme - TP2 of DSIR and meets the Sukhbhadar River at village Khun. The Sukhbhadar River is one of the major river passing through TP1 and TP2. The Sukhbhadar Dam is one of the major Dam on the Sukhbhadar River and it is approximately 100 km upstream of the study area. The average annual rainfall on the downstream side of the Dam and of DSIR region is 701 mm. In the year 2019 August there was heavy rainfall. The releases from the Sukhbhadar Reservoir and rainfall resulted into catastrophic floods in these regions of DSIR. As DSIR is special region proposed to develop for industrial activities, floods may cause millions of dollars damages in future. In the present study 1- Dimensional Hydrodynamic modelling has been carried out for recent flood of year 2019. MIKE 11 software is used to model 1D unsteady flow for this event. The shape file of the Sukhbhadar River reach from Sukhbhadar Dam to DSIR region is given as input and cross sections at regular interval of 100 m are generated from AW3D30 DEM. Sukhbhadar Dam release hydrograph is given as upstream boundary condition and predicted Tidal data of Bhavnagar is given as downstream boundary condition. It has been observed that from Sukhbhadar Dam to 55481.3 chainage slope is 1 in 698. For 55481.3 to 1611.33 chainage the slope is 1 in 3591. The area of DSIR is almost flat. As observed during recent flood of year 2019, entire DSIR area (920 sq km) was fully inundated. It has been felt that strong mitigation measures are required to cope up with these flooding situations. In the present analysis embankment or retaining wall on either bank of the river has been considered as one of the flood mitigation measure. The height of retaining wall to prevent these DSIR areas vary from 1 m to 25 meters up to 2500 cumec releases from the dam. This solution may not be economical hence it is proposed to take advantage of parallel natural streams and ponds to conserve flood water. This solution seems to be more practical and economical. The paper analyze flood of DSIR region as without proper flood measures it is difficult to develop this region.

How to cite: Yadav, S., Borana, S., Jariwala, N., and Chaurasia, S. R.: Assessment of flood effect on semi-arid special investment region using 1D hydrodynamic modeling, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-2524,, 2020.

NH1.3 – Atmospheric Electricity, Thunderstorms, Lightning and their effects

EGU2020-7768 | Displays | NH1.3

Electric Field Sensor for Small Unmanned Aerial Vehicles

Stefan Chindea and Keri Nicoll

Characterisation of the vertical variation in the atmospheric electric field has been made for many decades, but normally in an ad-hoc manner, using instrumented weather balloons or manned aircraft, which are expensive to fly.  Such vertical measurements are required to measure the ionospheric potential and to characterise electric fields with clouds (both thunderstorm and non thunderstorm clouds) to understand the charging processes within them. 

Advances in electronics and battery technology has meant that small Unmanned Aerial Vehicles (UAVs) have now become available as a new science platform. These measurement platforms address many of the problems associated with manned aircraft while allowing in-situ measurements with an increased level of control and repeatability when compared to weather balloons. Despite their potential advantages, one of the main challenges to using UAVs for atmospheric electricity research is the lack of small, lightweight sensors which are commercially available. To overcome this barrier, this work describes the development of a lightweight, miniaturised electric field sensor to be integrated with a small UAV (<7kg, wingspan 2m). 

The sensor has been designed to allow measurements of the electric field intensities typical of non-thunderstorm low altitude (<6000 ft) clouds with a typical range of 0-2.5kV/m. It is based on the concept of an electric field mill, but with a translational shield rather than a rotating vane model. This allows the sensor to fit neatly within the wing of a small UAV, rather than the need to be mounted in the nose.  A custom designed 3D printed housing contains all elements of the sensor package, with the translational shield movement and data logging controlled by an onboard programmable microcontroller. This work will focus on the details regarding the experimental characterisation of the sensor package with a particular focus on the key influences of the integration with the airborne platform.

How to cite: Chindea, S. and Nicoll, K.: Electric Field Sensor for Small Unmanned Aerial Vehicles, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-7768,, 2020.

EGU2020-18767 | Displays | NH1.3

Atmospheric electric field in the Atlantic marine boundary layer: first results from the SAIL project

Susana Barbosa, Mauricio Camilo, Carlos Almeida, José Almeida, Guilherme Amaral, Karen Aplin, Nuno Dias, António Ferreira, Giles Harrison, Armando Heilmann, Luis Lima, Alfredo Martins, Igor Silva, Diana Viegas, and Eduardo Silva

The study of the electrical properties of the atmospheric marine boundary layer is important as the effect of natural radioactivity in driving near surface ionisation is significantly reduced over the ocean, and the concentration of aerosols is also typically lower than over continental areas, allowing a clearer examination of space-atmosphere interactions. Furthermore, cloud cover over the ocean is dominated by low-level clouds and most of the atmospheric charge lies near the earth surface, at low altitude cloud tops.

The relevance of electric field observations in the marine boundary layer is enhanced by the the fact that the electrical conductivity of the ocean air is clearly linked to global atmospheric pollution and aerosol content. The increase in aerosol pollution since the original observations made in the early 20th century by the survey ship Carnegie is a pressing and timely motivation for modern measurements of the atmospheric electric field in the marine boundary layer. Project SAIL (Space-Atmosphere-Ocean Interactions in the marine boundary Layer) addresses this challenge by means of an unique monitoring campaign on board the ship-rigged sailing ship NRP Sagres during its 2020 circumnavigation expedition.

The Portuguese Navy ship NRP Sagres departed from Lisbon on January 5th in a journey around the globe that will take 371 days. Two identical field mill sensors (CS110, Campbell Scientific) are installed on the mizzen mast, one at a height of 22 m, and the other at a height of 5 meters. A visibility sensor (SWS050, Biral) was also set-up on the same mast in order to have measurements of the extinction coefficient of the atmosphere and assess fair-weather conditions. Further observations include gamma radiation measured with a NaI(Tl) scintillator from 475 keV to 3 MeV, cosmic radiation up to 17 MeV, and atmospheric ionisation from a cluster ion counter (Airel). The 1 Hz measurements of the atmospheric electric field and from all the other sensors are linked to the same rigorous temporal reference frame and precise positioning through kinematic GNSS observations.

Here the first results of the SAIL project will be presented, focusing on fair-weather electric field over the Atlantic. The observations obtained in the first three sections of the circumnavigation journey, including Lisbon (Portugal) - Tenerife (Spain), from 5 to 10 January, Tenerife - Praia (Cape Verde) from 13 to 19 January, and across the Atlantic from Cape Verde to Rio de Janeiro (Brasil), from January 22nd to February 14th, will be presented and discussed.

How to cite: Barbosa, S., Camilo, M., Almeida, C., Almeida, J., Amaral, G., Aplin, K., Dias, N., Ferreira, A., Harrison, G., Heilmann, A., Lima, L., Martins, A., Silva, I., Viegas, D., and Silva, E.: Atmospheric electric field in the Atlantic marine boundary layer: first results from the SAIL project, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-18767,, 2020.

EGU2020-8037 | Displays | NH1.3

Measuring the electrical and optical properties of fog using balloon borne instrumentation in the UAE

Graeme Marlton, Giles Harrison, Keri Nicoll, and Maarten Ambaum

Countries in arid and desert climates that have small amounts of rainfall each year use cloud seeding techniques to enhance the little rainfall that is present. Typically, this is achieved by seeding the cloud with hygroscopic nuclei to increase the rainfall. A possible alternative method is to inject the cloud with electric charge, which has been shown in models to alter the droplet size and distribution and influence rainfall properties.

Here, in-situ observations of the electrical and optical properties of clouds are described from a desert site. These are used to inform droplet growth models. For this, a yearlong campaign, during which 10 weather balloons carrying electric charge and optical sensors were launched through fog layers from Abu Dhabi airport, United Arab Emirates. Here we present 2 case studies. The first is a clear air ascent comparison between the desert site at Abu Dhabi and a temperate site in northern Finland. The second is a fog comparison between Abu Dhabi and a temperate site in the United Kingdom

The results show that the fogs in Abu Dhabi are highly charged with a charge density of 0.1-1 nC m-3 as opposed to the charge densities of fogs in Northern Hemisphere temperate regions which have a typical charge density of 10 pC m-3. The droplet concentration in the Abu Dhabi fog case study is significantly smaller, approximately 150 cm-3 as opposed to droplet concentrations of 300-400 cm-3 in fog over a temperate site.

The results suggest that dust contributes strongly to the atmospheric electrical conditions in the UAE region, due to charging of the dust tribo-electrically. This dust charge may also affect the droplet distribution within the fog. These new measurements of the vertical profile of charge through fog layers in desert climates will be used to improve understanding in droplet growth models.

How to cite: Marlton, G., Harrison, G., Nicoll, K., and Ambaum, M.: Measuring the electrical and optical properties of fog using balloon borne instrumentation in the UAE, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-8037,, 2020.

EGU2020-21073 | Displays | NH1.3

Ground-based measurements of turbulence in electrified clouds

Evgeny Mareev, Vladimir Klimenko, Lev Lubyako, Mariya Shatalina, Svetlana Dementyeva, and Nikolay Ilin

A problem of the electric field dynamics in turbulent electro-active clouds (Cumulus, Stratus, Cumulonimbus) is one of the most relevant and complex problems of dynamical meteorology and atmospheric electricity. This problem is important for the study of intense large-scale electric field and its fluctuations that may lead to high-energy particle flows and lightning discharges, for electric current parameterization. Direct field measurements in convective clouds with a developed electrical structure are very difficult; so one of urgent tasks is the development of remote sensing methods for turbulence characteristics in electro-active clouds.

The growth of a large-scale electric field in a turbulent atmosphere is caused by the generation of an electric charge on colliding particles (hydrometeors and dust). Meanwhile, observations (including preliminary observations of the authors) and theoretical studies (Mareev and Dementyeva, 2017) show that intensification of thunderstorm activity can be associated with increased turbulence in the cloud. This paper presents new ideas and results of experimental and theoretical studies of the role of turbulence in electro-active clouds.

The main attention is paid to complex remote observations of different types of clouds with an experimental set-up including the microwave radiometers of 3 cm and 8 mm wavelengths (with a time resolution of order of one second), the network of electrostatic fluxmeters spaced by several kilometers each from another, and the meteorological radar. The data of recent several years were used for analysis. Note that recently space-borne passive microwave radiometry of intense convective clouds (see, for example, Peterson et al., 2017) attracted more attention compared to ground-based microwave observations. A principal idea of our approach is to use the wave-length channels allowing us to reveal both optically thick and optically transparent cloud events from the data on fluctuations in the brightness temperature of the atmosphere.

A special attention was paid to comparative analysis of the turbulence characteristics in thunderclouds and in clouds that do not have a developed electrical structure. The spectral characteristics of electric field and brightness fluctuations were found to be associated with atmospheric air turbulence and mostly are quantitatively described by Kolmogorov-type spectra. Compared with ordinary Cumulus and Stratus clouds, a limited band near a frequency of ~ 0.01 Hz with a higher level of fluctuations is distinguished in the spectral density of fluctuations in the brightness temperature of thunderclouds. The spectra of fluctuations of the electric field caused by thunderclouds, as well as turbulence interior thundercloud, are significantly different from the spectra caused by ordinary Cumulus and layered clouds.

The work was supported by the Russian Foundation for Basic Research (projects no. 19-05-00975 and 18-45-520010).


Mareev E.A., Dementyeva S.O. (2017), The role of turbulence in thunderstorm, snowstorm, and dust storm electrification. Journal of Geophysical Research: Atmospheres, V. 122, No. 13, P. 6976-6988. doi: 10.1002/2016JD026150.

Peterson M., Liu C., Mach D., Deierling W., Kalb C. (2015), A method of estimating electric fields above electrifi_ed clouds from passive microwave observations. J. Atmos. Ocean. Tech., V.32 (8), P.1429-1446. doi: 10.1175/ JTECH-D-14-00119.1.

How to cite: Mareev, E., Klimenko, V., Lubyako, L., Shatalina, M., Dementyeva, S., and Ilin, N.: Ground-based measurements of turbulence in electrified clouds, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-21073,, 2020.

This full-year study spanning portions of 2017-18 quantifies GOES-16 Geostationary Lightning Mapper (GLM) flash detection efficiency (DE) in central Florida using the Kennedy Space Center Lightning Mapping Array (LMA). Findings support the expectation that about 70% of all flashes are reported when averaged over all thunderstorms and times-of-day. When quantified as a function of LMA flash parameters, GLM exhibited an average of 40% DE for small (main channel length of 5-8 km), and even lower DE for shorter-length and/or short-duration (less than 200 milliseconds) flashes. Conversely, GLM exhibited more than 95% DE for long-duration flashes with main channel lengths of 50-100 km. DE was somewhat lower during daylight and higher at night.  Flash size and duration, on average are shown to be a critical parameter influencing GLM detection.  Given that this behavior occurred for severe and non-severe storms, it is likely an important contributing factor to the low flash detection efficiency for storms with high flash rates (and resulting small/short flashes) associated with severe weather, thereby modulating the effects of optical scattering and absorption within cloud volumes.

These findings can be explained by the time-evolution of cloud-top optical emissions derived from observations using the Lightning Imaging Sensor (LIS) onboard the Tropical Rainfall Measuring Mission (TRMM) Satellite. Specifically, LIS group area, energy density, and cloud-top energy in intra-cloud flashes, on average, reached a local maximum value in the very first few milliseconds of a flash and fell to their minimum values at around 10-20 milliseconds into the flash. After that, all parameters gradually increased over the next 80-100 milliseconds to reach the initial values, and then continued to increase for longer-duration flashes. In addition, statistical simulations based on long-term LIS group area observations indicate that about half of the above-threshold light sources are smaller than a LIS pixel (~ 4 km x 4 km) and are the smallest during initial breakdown in IC flashes.

These observations have implications for expectations about the performance of all satellite lightning observing instruments that are based on optical observations operating in the near-IR portion of the optical spectrum.  The specific values for optical source size and cloud-top energy provided by this study, as a function of time-in-flash, should help refine the expectations for the performance of the upcoming Lightning Imager on the Meteosat Third Generation geostationary satellite.


How to cite: Cummins, K. and Zhang, D.: Flash size and within-flash time evolution of cloud-top optical emissions: Implications for satellite-based lightning observations, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-4225,, 2020.

EGU2020-12408 | Displays | NH1.3

Simulating collisions of charged cloud drops in an ABC flow

Torsten Auerswald and Maarten Ambaum

Calculating the electric force between cloud drops is not straightforward. Since water drops are conducting, the electric force is not just simply the force between point charges, but instead the charge in each drop induces an infinite number of image charges in the other drop. The effect of these image charges can cause the electric force between two like charged cloud drops to become attractive on very short distances, when only applying Coulomb's law would result in a repulsive force. The attractive effect of image charges could potentially increase the collision rate of cloud drops. Within the United Arab Emirates Rain Enhancement Program (UAE REP) we are investigating the potential for rain enhancement by charging clouds.

Simulating the behaviour of cloud drops is numerically very expensive. A large number of drops needs to be simulated to obtain stable collision statistics. Additionally, the drops move in a complex turbulent environment with eddies spanning several orders of magnitude in size. Simulating the turbulent flow alone is an expensive task. Because of the typical sizes of cloud drops, their motion is predominantly influenced by the smallest turbulent scales in the flow. Therefore, Direct Numerical Simulation (DNS) is necessary and used to simulate the influence of turbulent flow on drop motion. In this work, instead of using DNS, we use an ABC flow to simulate the turbulent effect on cloud drops. This simple approximation for the turbulent flow allows to simulate the drop motion using much less computational resources then needed by DNS and therefore, allows to include the very expensive effect of electrical drop charge in our simulation of colliding drops in a turbulent environment.

To investigate the effect of electrical charge on drop collisions, a Lagrangian particle code for the interaction of cloud drops is used. It calculates the motion of individual drops based on the aerodynamical force due to the ABC flow and the gravitational force and registers drop collisions from which collision statistics can be calculated. In the cloud model all drops carry positive charges. The effect of the electric force is calculated by an approximation which uses Coulomb's law for the effect of the point charges and an additional term to approximate the effect of image charges which produce an attractive force on short distance.

Results for the collision kernel with and without charge will be presented. The effect of the additional term to Coulomb's law will be shown for different drop sizes and drop charges. It will be discussed if the attractive force for like charged drops on short distances can lead to an enhancement in drop collisions and under which conditions the effect is the largest.

How to cite: Auerswald, T. and Ambaum, M.: Simulating collisions of charged cloud drops in an ABC flow, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-12408,, 2020.

EGU2020-20611 | Displays | NH1.3

Lightning Clustering to Study Regional Variations in Thunderstorm Characteristics

Jeff Lapierre and Michael Stock

Many studies have shown that the characteristics of lightning such as size and peak current differ by geographical region as well as between ocean and continental thunderstorms. For example, several studies have shown that the lightning in oceanic thunderstorms are generally larger and have lightning with higher peak currents than in continental thunderstorms. In this study, as opposed to individual lightning flash characteristics, we focus on how thunderstorm characteristics change for various regions. We develop a lightning clustering algorithm that takes individual lightning strokes and creates thunderstorms based on their spatiotemporal proximity. We use lightning data from the Earth Networks Total Lightning Network and compare storms throughout regions of the U.S.A. and Europe. Once these thunderstorms are obtained, we can regionally categorize them and compare various characteristics (size, duration, flash rate, polarity, IC/CG ratio, etc.) to determine if any differences stand out. In this presentation, we will discuss the clustering algorithm used, analyze the results of the study, and discuss implications.

How to cite: Lapierre, J. and Stock, M.: Lightning Clustering to Study Regional Variations in Thunderstorm Characteristics, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-20611,, 2020.

EGU2020-6988 | Displays | NH1.3 | Highlight

Lightning, Evolution and Biology

Colin Price, Earle Williams, Gal Elhalel, and Dave Sentman

Most electrical activity in vertebrates and invertebrates occurs at extremely low frequencies (ELF), with characteristic maxima below 50Hz.  The origin of these frequency maxima is unknown and remains a mystery.  We propose that over billions of years during the evolutionary history of living organisms on Earth, the natural electromagnetic resonant frequencies in the atmosphere, continuously generated by global lightning activity, provided the background electric fields for the development of cellular electrical activity.  In some animals the electrical spectrum is difficult to differentiate from the natural background atmospheric electric field produced by lightning.  In this paper we present evidence for the link between the natural ELF fields and those found in many living organisms, including humans.

Price, C., E. Williams, G., Elhalel and D. Sentman, 2020:  Natural ELF Fields in the Atmosphere and in Living Organisms, Int. J. Biometeorology, in press.

How to cite: Price, C., Williams, E., Elhalel, G., and Sentman, D.: Lightning, Evolution and Biology, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-6988,, 2020.

EGU2020-3337 | Displays | NH1.3 | Highlight

Probability of lightning strikes to wind turbines in Europe during winter months

Gerhard Diendorfer

Upward lightning triggered by elevated objects, such as wind turbines (WT), may increase significantly the number of lightning strikes to these objects. In the recently publishes 2nd edition of the international standard IEC 61400-24 an environmental factor CDWL for winter lightning conditions was introduced to account for this additional lightning risk in the lightning exposure assessment of a WT. Values for CDWL should be 4 (in medium winter lightning activity areas) or 6 (high activity areas) or even higher in special cases. The main challenge is to get reliable data about the winter lightning activity for a given region and for first estimates maps of winter lightning activity for the continents are given in IEC 62400-24, Annex B.

A different approach is used in this contribution. As there is already a high number of WT installed in Europe, we have investigated the number (percentage) of existing WT that was at least struck one time in the winter periods of 2017/18 an 2018/19 based on data of the EUCLID lightning location system.

We have extracted the locations of 10.225 WT sites in Europe in the area from 45°N - 50°N and 10°W -30°E form OpenStreetMap database. Then we checked if there were any lightning strikes located by EUCLID within a 0.003° circular area (is about a 300 m radius) around each of these turbines during the cold season (October to April) in 2017/18 and 2018/2019, respectively. Out of the 10.225 WT 1.131 (11,1 %) and 913 (8,9 %) have been struck by lightning in cold season 2017/18 and 2018/19, respectively. It is worth noting, that only 101 WT (1%) were struck in both seasons, indicating that it is more a dependency on regional meteorological conditions changing from year to year, rather than on a specific group of WT. EUCLID detected flashes are likely to represent only about one half of the real occurring upward flashes from the WT. ICCOnly type upward lightning, which are discharges with current waveforms not followed by any return strokes are typically not detected by lightning location systems, and on instrumented towers this type of discharges makes up about 50% of all upward lightning. But there is a high chance, that a large fraction of this ICCOnly discharges were triggered by the same WT, where EUCLID detected some strokes.

In terms of dependency of the altitude of the WT site above sea level we observe a clear increase of probability of WT lightning with increasing altitude. About 10 % (29/315) of the 315 WT at altitudes up to 50 m ASL are struck by lightning increasing to almost 50 % (15/31) for WT at sites of 950 to 1000 m altitudes ASL. No clear trend is observed for higher altitudes, likely due to the low number of WT above 1000 m.

The obtained 10 % of the WTs triggering at least one upward lighting per cold season demonstrates the high probability of lightning to WT and emphasizes the need of proper protection of the WTs mechanical structure (rotor blades) as well as the entire electrical installation.

How to cite: Diendorfer, G.: Probability of lightning strikes to wind turbines in Europe during winter months, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-3337,, 2020.

EGU2020-4024 | Displays | NH1.3

Characteristics of North European winter lightning related to a high positive North Atlantic Oscillation index

Ivana Kolmašová, Kateřina Rosická, and Ondřej Santolík

The variability of winter climate in the North Atlantic region is predominantly driven by a large scale alternation of atmospheric masses between the Icelandic Low and Azores High pressure systems called the North Atlantic Oscillation (NAO) and characterized by the NAO index. The calculation of the NAO index is based on the difference between sea-level pressure strengths of the Azores High and the Icelandic Low. Unusually high positive values of the NAO index were observed to manifest themselves by above-average precipitation and severe winter storms over British Isles and other parts of northwestern and northern Europe.

In the last two decades, the winter season 2014/2015 exhibited the highest positive monthly NAO indexes. During this winter, newspapers in the UK, Germany, Poland, and Scandinavia reported extremely strong storms which caused huge power outages, damages of buildings, and collapses of traffic which paralyzed the daily life. As winter thunderstorms are also characterized by a higher production of very energetic lightning, we use the World Wide Lightning Location Network (WWLLN) data and investigate properties of lightning which occurred in the north European region from October 2014 to March 2015.  The dataset consists of more than 90 thousand lightning detections. We focus on spatial and temporal distribution of lightning strokes, their energies and multiplicity.

We have found that the diurnal distribution of lightning was random from November till February, while the afternoon peak typical for summer storms was noticeable only in October and March. The median energy of lightning strokes observed in October, November and March reached only about 10-20% of the median energy of strokes detected in December, January and February. The most energetic strokes were concentrated above the ocean close to the western coastal areas and appeared exclusively at night and in the morning hours.

How to cite: Kolmašová, I., Rosická, K., and Santolík, O.: Characteristics of North European winter lightning related to a high positive North Atlantic Oscillation index, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-4024,, 2020.

EGU2020-22302 | Displays | NH1.3 | Highlight

Nowcasting Lightning Occurrence Using Machine Learning Techniques: The Challenge of Identifying Outliers

Amirhossein Mostajabi, Declan Finney, Marcos Rubinstein, and Farhad Rachidi

Lightning is formed in the atmosphere through the combination of complex dynamic and microphysical processes. Lightning can have a considerable influence on the environment and on the economy since it causes energy supply outages, forest fires, damages, injury and death of humans and livestock worldwide. Therefore, it is of great importance to be able to predict lightning incidence in order to protect people and installations. Despite numerous attempts to solve the important problem of lightning prediction (e.g., [1]–[3]), the complex processes and large number of parameters involved in the problem lend themselves to the potential application of a machine learning (ML) approach.

We recently proposed a ML-based lightning early-warning system with promising performance [4]. The proposed ML model is trained to nowcast lightning incidence during any one of  three consecutive 10-minute time intervals and within a circular area of 30 km radius around a meteorological station. The system uses the real-time measured values of four meteorological parameters that are relevant to the mechanisms of electric charge generation in thunderstorms, namely the air pressure at station level (QFE), the air temperature 2 m above ground, the relative humidity, and the wind speed. The proposed algorithm was implemented using the data from 12 meteorological stations in Switzerland between 2006-2017 with a granularity of ten minutes. The stations were selected to be well distributed among different ranges of altitude and terrain topographies.

The algorithm requires the filtering out of a portion of the data which are identified as outliers. However, the process of the automatic identification of outliers is a challenging task which could also affect the model’s performance. In this presentation, we discuss this problem and present approaches that can be used to optimize the process.



[1]      D. Aranguren, J. Montanya, G. Solá, V. March, D. Romero, and H. Torres, “On the lightning hazard warning using electrostatic field: Analysis of summer thunderstorms in Spain,” J. Electrostat., vol. 67, no. 2–3, pp. 507–512, May 2009.

[2]      G. N. Seroka, R. E. Orville, and C. Schumacher, “Radar Nowcasting of Total Lightning over the Kennedy Space Center,” Weather Forecast., vol. 27, no. 1, pp. 189–204, Feb. 2012.

[3]      Q. Meng, W. Yao, and L. Xu, “Development of Lightning Nowcasting and Warning Technique and Its Application,” Adv. Meteorol., vol. 2019, pp. 1–9, Jan. 2019.

[4]      A. Mostajabi, D. L. Finney, M. Rubinstein, and F. Rachidi, “Nowcasting lightning occurrence from commonly available meteorological parameters using machine learning techniques,” npj Clim. Atmos. Sci., vol. 2, no. 1, p. 41, 2019.

How to cite: Mostajabi, A., Finney, D., Rubinstein, M., and Rachidi, F.: Nowcasting Lightning Occurrence Using Machine Learning Techniques: The Challenge of Identifying Outliers, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-22302,, 2020.

EGU2020-20990 | Displays | NH1.3 | Highlight

Ground-based lightning and AWS network system for alert of torrential rainfall and typhoon combined with micro-satellite constellation

Yukihiro Takahashi, Mitsuteru Sato, Hisayuki Kubota, Testuro Ishida, Meryl Algodon, Ellison Castro, Loren Estrebillo, Purwadi Purwadi, Gay Perez, Kozo Yamashita, Jun Matsumoto, and Jun-ichi Hamada

We have been developing a ground-based lightning and AWS network system under the projects of a SATREPS “ULAT” and e-ASIA in order to realize precise real-time monitoring and issuing alert for torrential rainfall and typhoon extreme based on international cooperation among Japan, Philippines, Indonesia and other SE-Asian countries supported by JST, JICA, PHL-Microsat and other funding. The intensification of lightning activity is precursor of typhoon growth. In these projects, we are constructing ground-based lightning and AWS—automated weather station—network system with 12 sites for VLF radio wave measurement in nation-wide of Philippines and with 50 sites for electrostatic field measurement in Metro Manila together with infrasound sensor. We are going to complete the installation of the sensors at most of the planned ~60 sites by the end of this year. We already started with installed sensors and achieved preliminary results for typhoon and thunderstorm measurement. We are also doing practice in operating our micro-satellite which can make rapid target pointing at high accuracy. Using the photos captured from the satellite, now we can reproduce the detailed 3-D structure of the cloud at best quality even compared to the latest radar system.

How to cite: Takahashi, Y., Sato, M., Kubota, H., Ishida, T., Algodon, M., Castro, E., Estrebillo, L., Purwadi, P., Perez, G., Yamashita, K., Matsumoto, J., and Hamada, J.: Ground-based lightning and AWS network system for alert of torrential rainfall and typhoon combined with micro-satellite constellation, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-20990,, 2020.

EGU2020-2752 | Displays | NH1.3

New and improved European satellite observation capabilities for hazardous weather to be available from 2022 onwards: Meteosat Third Generation (MTG)

Jochen Grandell, Thomas August, Dorothee Coppens, Gary Fowler, Mounir Lekouara, Rosemary Munro, and Bartolomeo Viticchie

EUMETSAT has provided the user community with more than three decades worth of satellite data, starting with the geostationary missions of the Meteosat First Generation, and since 2002 with the Meteosat Second Generation (MSG) series satellites.

The development of the next generation geostationary program, the Meteosat Third Generation (MTG), is now in its final stages. The MTG system will host a more advanced 16-channel VIS/IR Flexible Combined Imager (FCI) as well as a Lightning Imager (LI) on its geostationary imaging platform (MTG-I), whereas the sounding platform (MTG-S) will host the MTG InfraRed Sounder (IRS) and the Copernicus Sentinel-4 ultraviolet/near-infrared (UVN) sounding missions. The launch of the first two satellites MTG-I1 and MTG-S1 hosting the imaging and sounding instruments is foreseen in 2021 and 2023, respectively.

The new and improved capabilities will significantly enhance the potential for convective storm monitoring, from the earliest initial phases to full maturation and dissipation. In addition, as examples of dedicated applications where the improved capabilities will play a significant role, one can mention fog monitoring and especially the enhanced fire monitoring capability.

The presentation will give an overview of the MTG system, its observation missions, and the main improvements and novelties over Meteosat Second Generation (MSG) in terms of new missions and expected product performance. As a primarily Nowcasting mission, MTG will provide significant additions to the hazardous weather observations in the coming years. The emphasis of the presentation will be on the new observational capability provided by the Lightning Imager.

How to cite: Grandell, J., August, T., Coppens, D., Fowler, G., Lekouara, M., Munro, R., and Viticchie, B.: New and improved European satellite observation capabilities for hazardous weather to be available from 2022 onwards: Meteosat Third Generation (MTG), EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-2752,, 2020.

Previous studies suggested that lightning activity could be an indicator of Tropical Cyclone (TC) intensity change but their relationships vary greatly and at times appear contradictory. The importance of total lightning for TC intensification study and forecasting applications has also been pinpointed by several studies. Recently, we revisited this problem using 16 years of TRMM Lightning Imaging Sensor (LIS) measurements and found that reduced (elevated) inner-core total lightning marked rapidly intensifying (weakening) TCs, whereas outer rainband total lightning had opposite trends. It is also shown that the reduced lightning frequency in the inner cores of rapidly intensifying storms was coincident with reduced volumes of 30-dBZ radar reflectivity in the mixed-phase cloud region (-5 to -40 oC), suggesting the lack of large ice particles (e.g., graupel) in the inner cores of rapidly intensifying TCs (which is considered to be important for cloud electrification). To better understand the physical process responsible for these results, we have examined the vertical profiles of radar reflectivity, distribution of precipitation/convection, overshooting radar echo tops (CloudSat), and microwave ice scattering signatures provided by GPM and CloudSat overpasses. This data fusion exercise uniquely provides a more complete understanding of storm electrification, convective intensity, ensemble precipitation microphysics, and storm dynamics in relation to TC intensity change. For example, we have distinguished the convective and microphysical structures between rapidly intensifying (RI) TCs with and without enhanced lightning activity, RI and steady-state TCs, and RI and rapidly weakening TCs.

How to cite: Xu, W.: Changes of Lightning Activity and Vertical Structure in the Inner Core Preceding Tropical Cyclone Rapid Intensification , EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-4085,, 2020.

EGU2020-17913 | Displays | NH1.3 | Highlight

Analysis of Elves observations from about 2 years of ASIM operation.

Olivier Chanrion, Torsten Neubert, Chiara Zuccoti, Matthias Heumesser, Krystallia Dimitriadou, Francisco J. Gordillo, Francisco J. Perez-Invernon, Nikolai Østgaard, Andrey Mezentsev, and Victor Reglero

The Atmosphere-Space Interaction (ASIM) mission was launched on April 2, 2018 and installed on an external platform of the Columbus Module of the International Space Station the 13th.

The main objectives of the mission are to observe and study thunderstorms and their interaction with the atmosphere. ASIM embarks two main instruments pointing at Nadir, the Modular Multispectral Imaging Array (MMIA) observing in the visible and the Modular X- and Gamma- ray Sensor (MXGS) observing in the X- and Gamma-ray bands.

In this presentation we focus on observations made by the MMIA which includes two cameras operating in the bands 337/5 nm and 777.4/3 nm and three photometers operating in the bands 180-230 nm, 337/5 nm and 777.4/5 nm. Specifically, we analyze the short duration pulses recorded in the 180-230 nm band.

After about 2 years of operations, more than 2500 of such events were identified in the data. They are likely to be recordings of ELVEs (Emissions of Light and Very low frequency perturbation due to Electromagnetic pulse sources), occurring in the ionosphere in response to lightning currents.

We show the amplitude, spatial and temporal distributions of the events and compare the results with those of previous studies. We present an analysis of the temporal characteristics of the pulses themselves and of their delays regarding the parent lightning observed in the other ASIM photometers or in the GLD360 ground lightning detection network recordings. Finally, we compare some typical events with modeling.

How to cite: Chanrion, O., Neubert, T., Zuccoti, C., Heumesser, M., Dimitriadou, K., Gordillo, F. J., Perez-Invernon, F. J., Østgaard, N., Mezentsev, A., and Reglero, V.: Analysis of Elves observations from about 2 years of ASIM operation., EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-17913,, 2020.

EGU2020-15025 | Displays | NH1.3

High-speed UV imaging of elves and lightning from space: first simultaneous detections from the Mini-EUSO and ASIM instruments

Matteo Battisti, Enrico Arnone, Mario Bertaina, Marco Casolino, Olivier Chanrion, Christer Fuglesang, and Torsten Neubert and the Mini-EUSO team for the JEM-EUSO collaboration

The search for the physical mechanisms of lightning, transient luminous events and terrestrial gamma-ray flashes is receiving an extraordinary support by new space observations that have recently become available. Next to lightning detectors on geostationary satellites, new low orbit experiments are giving an unprecedented insight in the very source of these processes. Looking at the physics behind these new observations requires however to have a variety of different instruments covering the same event, and this is proving extremely challenging. Here, we present observations of UV emissions of elves and lightning taken for the first time simultaneously from the two instruments Mini-EUSO and ASIM operating on the international space station. Mini-EUSO was designed to perform observations of the UV-light night emission from Earth. It is a wide field of view telescope (44°x44° square FOV) installed for the first time on October 2019 inside the Zvezda Module of the ISS, looking nadir through a UV transparent window. Its optical system consists of two Fresnel lenses for light collection. The light is focused onto an array of 36 multi-anode photomultiplier tubes (MAPMT), for a total of 2304 pixels. Each pixel has a footprint on ground of ~5.5 km. The instrument is capable of single-photon counting on three different timescales: a 2.5 microsecond (D1) and a 320 microsecond (D2) timescale with a dedicated trigger system, and a 40.96ms timescale (D3) used to produce a continuous monitoring of the UV emission from the Earth. ASIM is an experiment dedicated to lightning and atmospheric processes. Its Modular Multispectral Imaging Array (MMIA) is made of an array of 3 high speed photometers probing different wavelength sampling at rates up to 100 kHz, and 2 Electron Multiplication Charge Coupled Devices (EM-CCDs) with a sub-km spatial resolution with an 80° FOV and recording up to 12 frames per second. Mini-EUSO detected several bright atmospheric events like lightning and elves, with a few km spatial resolution and different time resolutions, probing therefore different stages of the electromagnetic phenomena. Observations from Mini-EUSO were simultaneously captured by ASIM instruments, allowing for the first time to compare and complement the capabilities of the two instruments with a time inter-calibration based on unambiguous series of lightning detections.

How to cite: Battisti, M., Arnone, E., Bertaina, M., Casolino, M., Chanrion, O., Fuglesang, C., and Neubert, T. and the Mini-EUSO team for the JEM-EUSO collaboration: High-speed UV imaging of elves and lightning from space: first simultaneous detections from the Mini-EUSO and ASIM instruments, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-15025,, 2020.

EGU2020-18845 | Displays | NH1.3 | Highlight

Analysis of Blue Discharges in Thunderclouds

Krystallia Dimitriadou, Olivier Chanrion, Torsten Neubert, Matthias Heumesser, Alain Protat, Valentin Louf, Hugh Christian, Richard Blakeslee, Chris Köhn, Nikolai Østgaard, and Victor Reglero

The Modular Multispectral Imaging Array (MMIA) of the Atmosphere-Space Interactions Monitor (ASIM) contains 3 photometers and 2 cameras, that monitors electrical discharges in and above thunderstorms. The 3 photometers sample in the bands:  337/4 nm, the VUV band 180-230 nm and 777.4/5 nm at 100 kHz; and the 2 cameras record in the bands 337/5 nm and 777.4/3 nm, with a temporal resolution of 12 frames per second. The 337 nm band corresponds to the strongest line of N22P, the VUV band include part of the N2 LBH and the 777.4 nm band corresponds to the OI line which is the strongest emission line of lightning leader channel. Here, we analyse observations of flashes that are predominantly blue. We will discuss the leader/streamer nature of these flashes. The analysis incorporates satellite cloud observations and weather radar measurements for the characterization of the thunderstorm clouds and their phase of development. In our optical analysis we incorporate also comparisons with data from NASA’s Lightning Imaging Sensor on the ISS (ISS-LIS) and VAISALA’s lightning location network GLD360.

How to cite: Dimitriadou, K., Chanrion, O., Neubert, T., Heumesser, M., Protat, A., Louf, V., Christian, H., Blakeslee, R., Köhn, C., Østgaard, N., and Reglero, V.: Analysis of Blue Discharges in Thunderclouds, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-18845,, 2020.

EGU2020-10093 | Displays | NH1.3

Optical discrimination of sprite and lightning by use of green light from ~495-505 nm

Simon Ghilain, Martin Fullekrug, Francisco José Gordillo Vazquez, and Aleksandrs Sergejevs

Sprites are transient illuminations of the middle atmosphere above thunderclouds which often occur after intense lightning discharges. Here we report optical recordings of sprites and lightning taken with a video camera and photometers in northern Colombia during October 2019.

Optical observations of sprites are often superimposed on the scattered light produced by the parent lightning discharge. This superposition of two optical sources can result in a misinterpretation of the photometer recordings, for example the determination of the rise time of an optical waveform.

Here we propose to use the green light emissions from ~495-505 nm to discriminate between sprite and lightning. This experimental discrimination has become possible because recent modeling studies suggest that lightning emits green light whilst sprite do not emit green light (Gordillo Vazquez et al., 2011; Xue et al., 2015).

The optical signals are detected by a white light video camera and a photometer which is fitted with a ~495-505 nm band pass filter to detect green light. The observed lightning discharges are characterized by significant green emissions in the ~495-505 nm wavelength band. These green emissions are part of the diffuse glow detected by the video camera which is caused by the scattered light from the lightning discharge. This light is scattered during its propagation through the atmosphere which is most likely caused by aerosols, for example related to the ambient humidity and dust. The majority of sprite observations are contaminated by such a diffuse glow with significant ~495-505 nm emissions. The observation of one particular sprite does not exhibit any significant ~495-505 nm emissions and it is therefore attributed to a ‘pure sprite’. The rise time of these optical emissions and the characteristics of other wavelengths recorded by several photometers will be reported for this particularly pure sprite event.

The knowledge gained from these ground-based observations may assist the interpretation of measurements with photometers onboard the ASIM payload on the International Space Station and the forthcoming TARANIS satellite.   



Gordillo-Vazquez, F.J., Luque, A. and Simek, M.(2011). Spectrum of sprite halos. Journal of Geophysical research, 116, A09319. doi: 10.1029/2011JA016652.

Xue, S., Yuan, P., Cen, J., Li, Y. and Wang, X.(2015). Spectral observations of a natural bipolar cloud-to-ground lightning. Geophysical Research Letters, 120, 1972–1979. doi:10.1002/2014JD022598

How to cite: Ghilain, S., Fullekrug, M., Gordillo Vazquez, F. J., and Sergejevs, A.: Optical discrimination of sprite and lightning by use of green light from ~495-505 nm, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-10093,, 2020.

EGU2020-19320 | Displays | NH1.3 | Highlight

Modeling terrestrial gamma-ray flashes observed by ASIM

Joseph Dwyer

The Atmosphere-Space Interactions Monitor (ASIM) on the International Space Station is providing important observations of terrestrial gamma-ray flashes (TGFs), including new measurements of optical emissions associated with TGFs and new measurements of multi-pulsed TGFs.  TGFs are thought to be produced by bremsstrahlung emissions from relativistic runaway electrons accelerated inside thunderstorms.  However, the exact mechanisms for generating the large number of runaway electrons required to account for the observed TGF luminosities remains an active area of debate.  Two mechanisms being considered are cold-runaway electron production by streamer heads or leader tips in the high-field regions near lightning, and the self-sustained production of runaway electrons by relativistic feedback involving backward propagating runaway positrons and backscattered x-rays.  Because both mechanisms may require the presence of lightning leaders inside thunderstorms -- for the cold-runaway mechanism to emit the runaway electrons and for the relativistic feedback mechanism to drive the electric field above the feedback threshold -- it has been challenging to test which TGF production mechanisms are occurring.  The new ASIM TGF observations should help constrain TGF models and possibly identify which mechanisms are primarily responsible for the runaway electron production.  In this talk, I will present new TGF modeling results and compare them with available ASIM observations.   

How to cite: Dwyer, J.: Modeling terrestrial gamma-ray flashes observed by ASIM, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-19320,, 2020.

EGU2020-2467 | Displays | NH1.3

Source Altitudes of Optical Emissions Associated with TGFs

Matthias Heumesser, Olivier Chanrion, Torsten Neubert, Krystallia Dimitriadou, Christoph Köhn, Francisco J. Gordillo-Vazquez, Alejandro Luque, Francisco Javier Pérez-Invernón, Hugh Christian, Richard J. Blakeslee, Nikolai Østgaard, Andrey Mezentsev, and Martino Marisaldi

Terrestrial Gamma-Ray Flashes (TGFs) observed from space appear to be generated after a few milliseconds of optical activity and before the onset of a main optical pulse. The pre-activity is thought to be from a propagating leader and the main optical pulse the emissions from the ensuing stroke. Scattering of photons in the cloud increases the rise time and durations of the pulses and thus allows for estimates of their optical path from their sources.

In this presentation we estimate the depth inside thunderclouds of pulses associated with more than 100 TGFs observed by the Atmosphere-Space Interactions Monitor (ASIM) on the International Space Station (ISS). The observations are in narrow bands at 337 nm, to include the strongest line of N22P and 777.4 nm of OI, considered a strong lightning emission line. With the assumption that the sources are instantaneous and at single points within a cloud, we find optical paths for the events by using typical cloud properties. Combined with cloud top heights from a recent study on TGF producing thunderstorms, this gives an estimate at which altitude the optical detections are produced.

Data from VAISALA’s lightning location network GLD360 and NASA’s Lightning Imaging Sensor on the ISS (ISS-LIS) will be used to assess the results from the optical analysis. This includes investigations of the correlations between TGF durations, detected peak lightning current and optical path in the cloud.

How to cite: Heumesser, M., Chanrion, O., Neubert, T., Dimitriadou, K., Köhn, C., Gordillo-Vazquez, F. J., Luque, A., Pérez-Invernón, F. J., Christian, H., Blakeslee, R. J., Østgaard, N., Mezentsev, A., and Marisaldi, M.: Source Altitudes of Optical Emissions Associated with TGFs, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-2467,, 2020.

EGU2020-5556 | Displays | NH1.3

One TGF and two elves produced by the same thunderstorm system

Nikolai Ostgaard, Steve Cummer, Andrey Mezentsev, Torsten Neubert, Victor Reglero, Olivier Arnaud Olivier, Martino Marisaldi, Pavlo Kochkin, Nikolai Lehtinen, David Sarria, Carolina Maiorana, Chris Alexander Skeie, Anders Lindanger, Yunjiao Pu, Freddy Christiansen, Kjetil Ullaland, and Georgi Genov

On February 8, 2019 the Atmosphere-Space Interaction Monitor (ASIM) passed a thunderstorm system north east of Puerto Rico and observed a TGF and an Elve from the same lightning stroke at the very beginning of a lightning flash. A second Elve was observed 456 ms later but without any signature of a TGF about 300 km south-east of the first Elve.
The strokes associated with the two Elve events were detected by WWLLN and Vaisala, which allows for an absolute timing accuracy of the ASIM measurements of at least 100 us. Images of the lighting strokes support the source locations for the Elves and TGF.  
Both the rise time of the UV pulse by ASIM MMIA photometer and radio measurements from Puerto Rico indicate that the first stroke was an intracloud positive while the latter was a cloud-to-ground stroke.
The UV emissions from the Elves preceded the optical emissions in 777 nm by
50 us and 90 us, respectively. This can partly be explained by the scattering of 777 nm within the cloud.
Current moments derived from radio measurements at Puerto Rico and Duke University  indicate a fast (30 us) and large (200 kA) current pulse emitting an electromagnetic wave that produces an Elve and a slow (1-2 ms) current producing the optical signals.


How to cite: Ostgaard, N., Cummer, S., Mezentsev, A., Neubert, T., Reglero, V., Olivier, O. A., Marisaldi, M., Kochkin, P., Lehtinen, N., Sarria, D., Maiorana, C., Skeie, C. A., Lindanger, A., Pu, Y., Christiansen, F., Ullaland, K., and Genov, G.: One TGF and two elves produced by the same thunderstorm system, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-5556,, 2020.

EGU2020-8515 | Displays | NH1.3

Extreme TGF Imaging by ASIM

Víctor Reglero, Paul Connell, Javier Navarro, Christopher Eyles, Nikolai Ostgaard, Torsten Neubert, Ferran Fabro, Joan Montanya, Andrey Mezentsev, Olivier Chanrion, Freddy Christiansen, Pavlo Kochkin, and Martino Marisaldi

One year after the starting of ASIM operational phase, we have succeeded to perform accurate Imaging of 54 TGF.  Among them, some have been analysed at extreme imaging conditions in terms of TGF position at the MXGS partially coded field of view.  20 TGF events have angular distances larger than 40º respect to the MXGS FOV centre. Extreme cases at angular distances larger than 50º are presented. Validation of TGF position by WLN data is included in the discussion.

The canonical value of 32 LED cnts as the minimum fluency for TGF imaging defined during MXGS development was checked using low luminosity TGF.  At the present, we have succeeded to obtain imaging solution for 7 TGF with less than 20 cnts. A sample is presented with indication of position accuracy and S/N ratios.  

Last part of the presentation is the discussion of a TGF with a very large and asymmetric probability distribution at the MXGS FOV that suggest the TGF as an extended source. Imaging data projected to the Earth surface is compared with GOES data, showing that the TGF is at the edge of a large convective cell, close to the TGF imaging data map.  Therefore, we can conclude that for some bright TGF it is possible to estimate the TGF fireball dimensions generated by the iteration of TGF photons with local atmospheric asymmetric matter distributions. The presence of a large CZT tail is coherent with the size of the convective cell.

How to cite: Reglero, V., Connell, P., Navarro, J., Eyles, C., Ostgaard, N., Neubert, T., Fabro, F., Montanya, J., Mezentsev, A., Chanrion, O., Christiansen, F., Kochkin, P., and Marisaldi, M.: Extreme TGF Imaging by ASIM, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-8515,, 2020.

EGU2020-9152 | Displays | NH1.3

Observation of TGFs at High Latitude

Carolina Maiorana, Martino Marisaldi, Andrey Mezentsev, Martin Fullekrug, Serge Soula, Anders Lindanger, Chris Alexander Skeie, David Sarria, Pavlo Kochkin, Nikolai Lehtinen, Ingrid Bjørge-Engeland, Nikolai Østgaard, Kjetil Ullaland, Georgi Genov, Torsten Neubert, Freddy Christiansen, and Victor Reglero

Terrestrial Gamma-ray Flashes (TGFs) are short bursts of gamma radiation originating from thunderclouds; they propagate upwards and are then detected by satellites such as AGILE, Fermi and ASIM. ASIM is the first mission specifically designed for the study of thunderstorm-related phenomena (Neubert et al., 2019); being placed on the ISS, it can for the first time detect TGF events up to more than 51 degrees in latitude.

Among the previous missions, RHESSI was the one reaching the highest latitude: 38 degrees. We then consider “high-latitude” for ASIM the band between 35 and 51 degrees of latitude. 9 events have already been observed in this band, inside four distinct geographical regions. At such latitudes, TGFs are expected to experience greater absorption in the troposphere, which makes them more difficult to detect. Moreover, we expect an intrinsically lower production rate due to the lower lightning activity (Smith et al., 2010, Williams et al., 2006).

In this work we present the characteristics of those events, in the context of the global ASIM sample collected so far. We also examine whether the observed number of events is statistically compatible with the atmospheric absorption, taking into account the local flash activity and ASIM’s exposure at high latitude.

How to cite: Maiorana, C., Marisaldi, M., Mezentsev, A., Fullekrug, M., Soula, S., Lindanger, A., Skeie, C. A., Sarria, D., Kochkin, P., Lehtinen, N., Bjørge-Engeland, I., Østgaard, N., Ullaland, K., Genov, G., Neubert, T., Christiansen, F., and Reglero, V.: Observation of TGFs at High Latitude, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-9152,, 2020.

In designing the MXGS coded mask imager on the ASIM mission to the ISS many simulations of its performance were made using a model of TGF origin as a RREA in a vertical electric ffield at about 15 km altitude. One consequence was the prediction that imaging scatter background from high energy photons would be 15-20% of CZT detector counts, decreasing with TGF off-axis observation angle.

Analysis of the linear image reconstruction model shows the maximum scatter background to be 40% in some cases, with sources at the same off-axis angle having both small and large scatter background. The obvious reason to explain this asymmetry is that a TGF beam is not primarily vertical, but at large angles, and provokes an inference about TGF origin.

The phenomenon can be explained by TGF origin at the tips of lightning leader channels, resulting in a wide range of random beam angles, or in the macro electric ffield of the induced negative shfielding charge above a stormcloud. This charge might begin as concentrated near the top-centre of a stormcloud but should slowly spread out to form a torus-like charge with the greatest electric field on the circular boundary of the torus, over a range of angles from vertical to horizontal to downward - with many TGFs absorbed or expanding spherically as a low energy Compton Scatter Remant.

In this scenario the TGF would originate near the upper radial edge of the cloud, but not within it, either by lightning leader electron injection or electron positron injection from a cosmic ray shower, posing the question if this location of origin can be observed.

We made a study of over 6000 TGF locations from FERMI-WWLLN observations where the centroid centrepoint of the nearest lightning cluster to the TGF was located, allowing for wind drift, its RMSQ cluster radius determined, and its distance vector from the cluster centrepoint. If the cluster would represent stormcloud location and area, then the macro E-field scenario of TGF origin should result in an annular distribution of the TGF-WWLLN vector location, but convolved with the lightning location error distribution. We present the results here, showing there is indeed a significant increase in TGF origin at the outer boundary of stormcloud lightning clusters.

How to cite: Connell, P.: Using FERMI TGF observation data to show an enhanced likelihood of TGF origin at the edges of stormcloud lightning clusters, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-10077,, 2020.

EGU2020-4645 | Displays | NH1.3

Modelling the production of terrestrial gamma-ray flashes during the final leader step

Christoph Köhn, Olivier Chanrion, Heumesser Matthias, Krystallia Dimitriadou, and Torsten Neubert

Recent measurements by the Atmosphere-Space Interactions Monitor (ASIM) indicate that the production of energetic electrons and of subsequent terrestrial gamma-ray flashes (TGFs) occurs immediately prior to intracloud lightning breakdown. Inspired by this finding, we relate the production of high-energy particles to the occurrence of streamer coronas initiated during the final leader step when the leader is in the vicinity of the upper cloud charge layer. Therefore, we model the acceleration of electrons and the subsequent production of energetic photons in the electric fields of the two encountering streamer coronas which are initiated in the vicinity of the leader tip and of the charge layer. Applying a particle Monte Carlo code, we first initiate thermal electrons in the electric field of the leader tip and subsequently turn on the streamer coronas and simulate the acceleration of electrons from thermal energies to energies of several tens of MeV. We present the temporal evolution of the electron and photon energies and spectra, and discuss the role of the electric fields of the encountering streamer coronas. Finally, we relate our results to ASIM measurements and discuss the duration and the relative timing of TGF bursts.

How to cite: Köhn, C., Chanrion, O., Matthias, H., Dimitriadou, K., and Neubert, T.: Modelling the production of terrestrial gamma-ray flashes during the final leader step, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-4645,, 2020.

EGU2020-7957 | Displays | NH1.3

Meter-scale Measurements of VHF structure of natural leader streamers

Brian Hare, Olaf Scholten, Joseph Dwyer, Ute Ebert, and Sander Nijdam and the LOFAR CR KSP

We will present maps of negative leaders imaged in the 30-80 MHz band by the LOFAR radio telescope, which is a distributed radio telescope in the Northern Netherlands that can map lightning with meter length and nanosecond timing accuracy. These VHF images show that negative leaders emit bursts of VHF that are about 1-3 µs in duration, most likely in relation to leader stepping. The median time between bursts is around 40 μs, and the median distance is about 7.5 m. Each of these bursts contains around 3-10 discrete VHF pulses. 2/3 of these pulses are consistent with coming from the same location (with 1 meter location accuracy), and the other 1/3 come from up to 3 m away. These data are consistent with the hypothesis that these VHF bursts are due to corona flashes during leader stepping, that the discrete pulses we locate are due to the few very strongest streamers in the corona flash, and the majority of streamers in a corona flash are too weak to be observed as discrete VHF pulses. From these data, we estimate that the strongest streamers in a natural corona flash emit about 4x10-6 J in our 30-80 MHz band.

How to cite: Hare, B., Scholten, O., Dwyer, J., Ebert, U., and Nijdam, S. and the LOFAR CR KSP: Meter-scale Measurements of VHF structure of natural leader streamers, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-7957,, 2020.

EGU2020-20497 | Displays | NH1.3

Investigating Thunderstorm HF/VHF Radio Bursts with Weak Lower Frequency Radiation

Ningyu Liu and Joseph Dwyer

While the spectrum of lightning electromagnetic radiation is known to peak around 5-10 kHz in the very low frequency (VLF) range, intense high frequency/very high frequency (HF/VHF) radiation can be produced by various lightning related processes. In fact, thunderstorm narrow bipolar events (NBEs), which are capable of initiating lightning, are the most powerful HF/VHF sources in nature on Earth. But even for NBEs, the spectral intensity in HF/VHF is still many orders of magnitude weaker than that of lower frequencies (Liu et al., JGR, 124,, 2019). HF/VHF bursts with weak VLF signals, however, can also be produced by thunderstorms. These bursts may be related to the thunderstorm precursor events noted by Rison et al. (Nat. Commun., 7, 10721, 2016) and are also found to precede a large fraction of lightning initiation (Lyu et al., JGR, 124, 2994, 2019). They are also known as continual radio frequency (CRF) radiation associated with volcanic lightning (Behnke et. al., JGR, 123, 4157, 2018).


In this talk, we report a theoretical and modeling study to investigate a physical mechanism for production of those HF/VHF bursts. The study is built on the theory developed recently concerning the radio emissions from an ensemble of streamers (Liu et al., 2019). We find an ensemble of streamer discharges that develop in random directions can produce HF/VHF radiation with intensity comparable to those all developing in a single direction, but the VLF intensity is many orders of magnitude weaker. The results of our study support the conclusions of Behnke et. al (2018) that CRF is produced in the absence of large-scale electric field, it results in insignificant charge transfer, and it is caused by streamers. In the context of the HF/VHF bursts preceding lightning initiation (Lyu et. al, 2019), our results imply that highly localized strong field regions exist in thunderstorms and streamers take place in those regions, which somehow precondition the medium for lightning initiation.

How to cite: Liu, N. and Dwyer, J.: Investigating Thunderstorm HF/VHF Radio Bursts with Weak Lower Frequency Radiation, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-20497,, 2020.

It’s a common knowledge for the spark discharge researches that there are space leaders inside the negative leader streamer zone. They arise from plasma formations of the volume of about 1 cm3 which are called space stems. But there is no any established idea about how space stems form in conditions when the background electric field magnitude inside a negative leader corona is about three times less than the dielectric strength of air. In this study, we propose a new mechanism of space stem precursors (ionization centers, which are capable to generate positive streamers) formation which is based on the joint action of ionization and drifting processes. The most possible location of proposed mechanism realization is the external boundary of the negative corona streamer burst, where electric field strength reaches a maximum value. The process takes place in the presence of strongly inhomogeneous stochastic electric field relief, which is formed by chaotically positioned clusters of negative charge transported to the negative corona streamer burst periphery by the negative streamer heads. The last are emanated from the leader tip during the negative corona streamer burst finishing each step-formation process. The only thing needed for the space stem precursor formation is the increased level of streamer heads spatiotemporal appearance frequency inside the very small area of space, which scale is of the order of a few millimeters. One important conclusion derived from this study is that the relatively strong electric field strength, overabundance of negative charge, and increased level of both reduced electric field and detachment frequency, which accompany ionization center formation, facilitate survival and growth of positive streamers initiated from a space stem precursor. The model is applied to specify the range of conditions, under which space stem precursor genesis is possible, and to analyze times of its formation at the range of altitudes of 0-12 km.

This work was supported by the Russian Science Foundation (project 19-17-00183).

How to cite: Syssoev, A. and Iudin, D.: A possible mechanism of space stem precursors formation at the negative lightning leader corona streamer burst periphery, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-11022,, 2020.

EGU2020-699 | Displays | NH1.3

Meteorological Parameters of Thunderstorm Ground Enhancements

Ekaterina Svechnikova, Nikolay Ilin, and Evgeny Mareev

Thunderstorm ground enhancements (TGEs) are events of energetic particle flux increases, discovered and observed at the Aragats Research Station (Armenia). Energetic particles are accelerated and multiplied in the electric field of clouds, and may be registered by ground-based detectors. Analysis of the structure of thunderclouds producing TGEs is crucial for clarifying the mechanism of particle acceleration.

In the present study the hydrometeor dynamics are analysed on the basis of the state of the atmosphere modeling by means of Weather Research and Forecasting Model. Meteorological characteristics typical of TGE occurrence in the mountainous region of Aragats are discovered. A technique has been developed for estimation of the charge distribution in a cloud on the basis of comparison of the simulations and experimental data. The retrieved cloud electrical structure is used to estimate the dependence of the electrification process on the temperature and liquid water content.

An unusually low concentration of ice particles leads to the great importance of snow particles in the process of charge separation. A typical charge distribution in a TGE-producing cloud is found to be well approximated by a two-layered charge structure with a lower positive charge region formed by graupel particles and an upper negative region formed by snow particles. Characteristic charge density is 0.01 C/km^3 for graupel cluster and 0.02 C/km^3 for snow cluster. A vertical distance of about 1-2 km between the lower positive and upper negative layers is sufficient for the development of an energetic particle avalanche.

The obtained estimation of the hydrometeor content and the electrical structure of a TGE-producing cloud provides new evidence on particle acceleration mechanisms in the atmosphere and processes of charge distribution in mountainous conditions.

How to cite: Svechnikova, E., Ilin, N., and Mareev, E.: Meteorological Parameters of Thunderstorm Ground Enhancements, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-699,, 2020.

EGU2020-8562 | Displays | NH1.3

Microsensor for Atmospheric Electric Fields

Andreas Kainz, Wilfried Hortschitz, Matthias Kahr, Franz Keplinger, and Gerhard Diendorfer

Many phenomena of atmospheric electricity are still not well understood, as most of the processes involved can only be observed in real nature. For this purpose, reliable and stable measurements of the electric field strength are mandatory. While for high-frequency fields, there exists a large variety of equipment, in the quasi-static and especially static regime, such systems are scarce. The „standard“ device for the application is the electrostatic field mill which uses a rotating, electrically grounded shutter electrode to alternatingly expose and shield measurement electrodes to/from the electric field. While they achieve good-enough resolution, there are many inherent problems associated with the measurement principle, such as mechanical wear, massive field distortions, size and weight. As a consequence, they are typically installed at a fixed points and cannot be easily moved or mounted. Miniaturised field mills have minimised some of these issues, the shutter priniciple leads to very fragile structures.

We present an alternative way of measuring low-frequency and static electric fields (E-field), which does not suffer from the hindering drawbacks of field mills. The underlying mechanism converts the E-field to a mechanical oscillation of a microelectromechanical system (MEMS). This is achieved by applying an AC voltage to a compliant mechanical structure. As a result of the AC voltage, alternating charges accumulate at the surface of the MEMS. When exposed to the E-field, this leads to a force deflecting the structure at a known frequency. For this kind of active mechanism, the power consumption is minimal, since the current flow is practically zero. Therefore, the system can be used in a floating way without grounded connections and therefore minimum field distortions. The mechanical motion can then be read out optically, also to avoid field distortions and backaction. If the system is driven at the mechanical resonance, the quality factor can be exploited to boost the sensitivity. In this case the bandwidth of the system ranges from 0 Hz to twice the resonance frequency.

Several MEMS sensors with different resonance frequencies (ranging from ~100 Hz to ~1 kHz) have been fabricated and tested in the laboratory. The sensors have been mounted between two parallel field plates supplied with a DC voltage, which provides the static electric field. A tiny hole in one of the field plates allowed for optical readout of the sensor movement with a laser-Doppler vibrometer (Polytec MSA-400). The sensors have been tested for different field strengths (10 V/m – 30 kV/m) and different AC voltages (0.02 V – 20 V) confirming linearity in both quantities. In terms of field strength, a resolution as good as ~25 V/m was achieved for a sensor with a resonance frequency of 167 Hz. These promising results substantiate that this sensor is a potentially low-weight, low-cost alternative for classical field mills. The next steps will be to investigate long-term stability and environmental effects on the sensor (temperature, humidity) and, finally, installation and test in the open area during fair weather and thunderstorm activity.

How to cite: Kainz, A., Hortschitz, W., Kahr, M., Keplinger, F., and Diendorfer, G.: Microsensor for Atmospheric Electric Fields, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-8562,, 2020.

EGU2020-10160 | Displays | NH1.3 | Highlight

Ionisation effects on precipitation

R.Giles Harrison, Keri Nicoll, Maarten Ambaum, Graeme Marlton, Karen Aplin, and Michael Lockwood

Cloud processes leading to rainfall generation are suspected to be influenced by droplet charge. Droplet charging is abundant, and even in layer clouds, charging of droplets readily occurs at the horizontal cloud-air boundary. Droplet charging in such circumstances is proportional to the vertical current driven through the cloud by the global electric circuit. Small global circuit variations from natural influences, such as solar modulation of cosmic rays can be used to investigate this, but an alternative is presented by artificial introduction of ionisation. The atmospheric nuclear weapons test period, which reached its peak 1962-1964, caused exceptional anthropogenic disturbance to the global circuit, through the increased ionisation from steady sedimentation of stratospheric radioactive debris.

Measurements of the vertical current Jz made at Kew Observatory near London (51°28′N, 0°19′W) were several times greater than normal during 1962-1964, as a result of the widespread extra ionisation in the lower atmosphere. At Lerwick, Shetland (60°09′N, 1°08′W) where deposition of radioactive material occurred, the atmospheric electrical parameters were strongly affected by the enhanced ionisation. To investigate tropospheric ionisation effects on local cloud processes, rainfall days at Lerwick in 1962-64 have been analysed by considering reduced and enhanced ionisation periods. During the enhanced ionisation, the Lerwick rainfall distribution shifted towards heavier rainfall and is significantly different from the rainfall distribution for reduced ionisation days; the Lerwick cloud was also significantly optically thicker during the enhanced ionisation. This contrasts with other years of the Kew record, when Jz was relatively undisturbed. Whilst the ionisation conditions of 1962-64 were exceptional, controlled methods of enhancing tropospheric ionisation by non-radioactive means - such as corona emission - may nevertheless be promising for local rainfall modification, or even geoengineering of cloud properties.

How to cite: Harrison, R. G., Nicoll, K., Ambaum, M., Marlton, G., Aplin, K., and Lockwood, M.: Ionisation effects on precipitation, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-10160,, 2020.

EGU2020-1298 | Displays | NH1.3

A study of the effects of hail, snow and PM on Potential Gradient

Konstantinos Kourtidis, Athanassios Karagioras, Eleni Papadopoulou, Nikos Mihalopoulos, and Iasonas Stavroulas

We present here the study of six hail events and five snow events in Xanthi, N. Greece, on Potential Gradient (PG). All hail events occurred in the spring-summer season of the years 2011-2018. A decrease in PG has been observed which has been around 2000-3000 V/m during the three hail events which occurred concurrently with rain. In three events with no rain, the decrease has been varying between 60 and 6000 V/m. In the case of only 60 V/m drop, no concurrent drop in temperature has been observed, while for the other cases it appears that for each degree drop in temperature the drop in PG is 1000 V/m, hence it appears that the intensity of the hail event regulates the drop in PG, although we do not have hail amount measurements to validate this. Regarding snow events,  the situation is more complicated, with PG fluctuating rapidly between high positive and high negative values. We present also a preliminary study of the impact of PM1.0 and PM2.5 on PG from measurements performed during 2019. We acknowledge support of this work by the project “PANhellenic infrastructure for Atmospheric Composition and climatE change” (MIS 5021516) which is implemented under the Action “Reinforcement of the Research and Innovation Infrastructure”, funded by the Operational Programme "Competitiveness, Entrepreneurship and Innovation" (NSRF 2014-2020) and co-financed by Greece and the European Union (European Regional Development Fund).

How to cite: Kourtidis, K., Karagioras, A., Papadopoulou, E., Mihalopoulos, N., and Stavroulas, I.: A study of the effects of hail, snow and PM on Potential Gradient, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-1298,, 2020.

At about 22:43:30 BJT (Beijing Time = UTC + 8) on 13 August 2016, two amateur astronomers in Shikengkong, Guangdong province, and Jiahe County, Hunan province, respectively, fortunately captured a gigantic jet (GJ) event simultaneously and the GJ exact location could be triangulated. The parent thunderstorm was in a very humid environment [Precipitable Water (PWAT) in excess of 60 mm], featuring high convective available potential energy (CAPE) and weak 0-6 km vertical wind shear. The GJ occurred in the region with the coldest cloud top brightness temperature of −64 °C, suggesting the GJ was associated with strong vertical development of the thunderstorm. Vertical cross sections of radar reflectivity also show that the GJ occurred near the thunderstorm strong convection region as indicated by the results that a region of 25 dBZ (and 35 dBZ) in excess of the local tropopause (overshooting top in the parent thunderstorm) during a time window containing the GJ. The negative cloud-to-ground flashes dominated during the thunderstorm evolution. Three positive narrow bipolar events (NBEs) were detected within 30s before and after the GJ. It indicates that the NBEs were distributed between 11 and 13 km and occurred in the upper and middle layers of thunderstorm with radar reflectivity of 30-35 dBZ.

How to cite: Yang, J.: Analysis of a gigantic jet in southern China: morphology, meteorology, storm evolution, lightning and narrow bipolar events, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-1812,, 2020.

EGU2020-3264 | Displays | NH1.3

The mineralogical, microstructural, chemical characteristics of Recently Formed Fulgurite in Kinmen, Taiwan

Meng Ting-Ju, Kuo Li-Wei, Chen Chien-Chih, Huang Wen-Jeng, and Chen Tze-Yuan

Lightning is a common high-energy phenomenon. In particular, cloud-to-ground lightning (CG lightning) generates shock wave and electrical discharge on the ground and forms the associated geological evidence including melting and shock lamella on rocks, termed fulgurites. Because lightning strikes on different protolith (cohesive or non-cohesive rocks), Pasek et al. (2012) divided the fulgurites into four types: (I) sand fulgurites, (ii) soil/clay fulgurites, (iii) calcic-soil fulgurites, and (iv) rock fulgurites. Compared with the reported fulgurites derived from non-cohesive rocks, the recognition of rock fulgurites was rare and remains unclear. Here we report the detailed characterization of rock fulgurites formed in a very recent CG lightning event with microanalytical methods including optical microscope, Field-Emission Scanning Electron Microscope (FESEM), Transmission Electron Microscope (TEM), regular and synchrotron X-ray Powder Diffraction (XRD), and Raman spectroscope. We also provide a CG lightning energy dissipation model constrained by the observed current values. The CG lightning event (the current value is ~ 162 kA) took place on granitic gneiss in Kimen county, Taiwan, on May. 7th, 2018. Our results show that the rock fulgurites were characterized with a black-to-brown thin (~10 μm in thickness) glassy crust with some vesicles covering on the host rock. Hydrous sulfates, including jarosites and gypsums, were recognized to locally deposit on fulgurites, likely suggesting the presence of hydrothermal condition in near-surface exposures after the cessation of the CG lightning. Planer deformation features derived from high pressures (up to several GPa) were found in k-feldspar located beneath the glassy crust, suggesting the presence of shock waves also on the surface. In addition, the estimated melting energy for the observed fulgurite (~20 m2 in area with the thickness of 100 μm) is much less than one one-hundredth of the observed CG lightning. It supports the previous studies that documented most of the electrical discharge was dissipated into ground. Our study establishes a reference rock fulgurites data originated from CG lighting on granitic rocks set for future on-site drilling and presents an application of these data for studies of ancient rock fulgurite relicts.

How to cite: Ting-Ju, M., Li-Wei, K., Chien-Chih, C., Wen-Jeng, H., and Tze-Yuan, C.: The mineralogical, microstructural, chemical characteristics of Recently Formed Fulgurite in Kinmen, Taiwan, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-3264,, 2020.

Natural and artificial lakes are able to change the climate of their surroundings. These modifications are collectively known as lake effects and range from microscale to synoptic scale. The presence of the lake can cause negative effect on the local thunderstorm activity in summertime decreasing the convection and precipitation over lakes due to the greater stability created by the lower atmosphere and the colder surfaces of the lake [1, 2]. However, it also can have a positive impact on thundercloud generation when the temperature difference between air in 850 mb height and near earth's surface is more than 13 C causing instability in the atmosphere [3].


The main objective of the present study is to investigate the impact of Lake Fertő (Neusiedler See, located in Hungary and Austria) on local thunderstorm activity by applying statistical analysis on meteorological and lightning data and event studies. Data of the Blitzortung lightning location network, local meteorological data (temperature, precipitation) measured at stations around the lake, water temperature measured at Fertőrákos and temperature measured at 850 mb in Vienna station were used for the analysis. The local thunderstorm activity was investigated during summertime (May - September) in 2015, 2016 and 2017. Lightning distribution maps above and around the lake for the investigated period have been determined based on the Blitzortung data.


According to the lightning distribution maps we can not observe any positive impact of the lake on the lightning activity when water temperature was higher than the air temperature around the lake. Furthermore, we can not conclude that there is a clear negative effect of the lake on the lightning activity based on the lightning distribution maps when the air temperature is higher than the water temperature. Nevertheless, there are some months when it seems a clear border between the lightning activity measured above the lake and at the coast (e. g. in June and July 2015, June 2016). The negative effect also seems to appear in some cases of the investigated local individual thunderstorms, namely the thunderstorm activity is larger above the surrounding surface than directly above the lake. This seems to strengthen the hypothesis that "Deep convection is not often formed in summer above the lakes, and existing storms dissipate significantly when moving above the lakes due to the greater stability created by the lower atmosphere and the colder surfaces of the lake" [1].


[1] Lyons, W. A., Some effects of Lake Michigan upon sqall lines and summertime convention. Proc. 9th Conf. Great Lakes Research, Great Lakes Res. Div. Publ. No. 15, University of Michigan, 259–273, 1966

[2] Scott, R. W., & Huff, F. A. . Impacts of the Great Lakes on Regional Climate Conditions. Journal of Great Lakes Research, 22(4), 845–863., 1996

[3] Wilson, J. W. : Effect of Lake Ontario on precipitation. Mon. Wea. Rev. 105, 207–214., 1977

How to cite: Karapetyan, G. and Barta, V.: Investigation of the lake-effect on the local thunderstorm activity around the Lake Fertő, Hungary, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-10387,, 2020.

The electrification of mineral sand/dust particles during aeolian processes is a well-documented phenomenon both in natural settings and in laboratory experiments. When in motion, small airborne dust particles collide with other suspended particles or impact the surface through the kinetic energy they acquire from the ambient wind. Field experiments will be conducted in conjunction with the AMEDEE-2020 Analog Mars Mission, planned for November 2020 in the Ramon Crater in southern Israel and led by the Austrian Space Forum. During SANDEE, we will deploy a portable wind-tunnel (Katra et al., 2016) at the site, and record particle movements in conditions that simulate sand storms of varying speeds. We will use local Negev desert, as well as Mars-simulant, soil samples that will be placed inside the wind-tunnel. We will measure particles' dynamic, mineralogical and electrical characteristics as they are blown by wind inside the tunnel.  A JCI 114 portable electric field detector will be used to to measure the amplification of the ambient electric field during sand movement. A vertical array of traps oriented along the wind direction will be used for sampling particles, in order to calculate the related sand fluxes and to analyze particle characteristics. The experiment will be repeated at night under dark conditions, in order to observe if light is emitted from electrified dust, due to corona discharges.

We expect that SANDEE will help decipher wind-speed/aerosol/electrical charge relationships. These have practical implications for future Mars landers, because airborne sand particles are likely to interfere with communications and also to impede the energy output of solar panels due to the electrical adhesion of charged aerosol.

How to cite: Katra, I. and Yair, Y.: The SANDEE campaign: Electrical effects during sand transport by aeolian processes in the Negev desert and implications for Mars, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-20343,, 2020.

EGU2020-1788 | Displays | NH1.3

Lightning super-bolts in Eastern Mediterranean winter thunderstorms

Yoav Yair, Barry Lynn, Baruch Ziv, and Mordecai Yaffe

Superbolts are defined as lightning flashes that are a thousand times stronger than normal ones, and their occurrence is estimated to be less than 0.001% of total number of lightning on earth. The global distribution of these extremely powerful lightning flashes is remarkably different than that of regular lightning, which are concentrated in the well-known convective "chimneys" in tropical Africa, South-America and the maritime continent in South-East Asia. The physical mechanisms producing these powerful flashes remain unknown, and the puzzle is exacerbated by the fact that they are discovered mostly over oceans, in maritime winter storms.

The Mediterranean Sea is one of the most prolific regions where super-bolts occur, especially in the months November-January (Holzworth et al., 2019). We analyzed 8 years of lightning data obtained from the Israeli Lightning Detection Network (ILDN), defining a 200kA peak current threshold for superbolts. We mapped the spatial and temporal distribution of superbolts and their monthly frequency in winter season thunderstorms (DJF) in the eastern Mediterranean, and identified the meteorological and microphysical circumstances in such storms.

Our working hypothesis is that large amounts of desert dust aerosols, coming from the Sahara Desert, are ingested into maritime winter storms over the eastern Mediterranean. The large dust contributes to convective invigoration, enhanced freezing and efficient charge separation, implying that superbolts are more likely to occur in the presence of large dust. We will present the results of simulation conducted using the WRF-ELEC numerical model, and WRF with spectral bin microphysics coupled with Lynn et al.'s (2012) Dynamic Lightning Scheme (DLS) and the Lightning Potential Index (Yair et al., 2010; LPI), for selected case studies when an enhanced fraction of superbolts was observed.


Holzworth, R. H., McCarthy, M. P., Brundell, J. B., Jacobson, A. R., and Rodger, C. J. (2019). Global distribution of superbolts. J. Geophys. Res. Atmos., 124., doi:10.1029/2019JD030975.

Lynn, B., Y. Yair, C. Price, G. Kelman and A. J. Clark (2012). Predicting cloud-to-ground and intracloud lightning in weather forecast models. Weather and Forecasting, 27, 1470-1488, doi:10.1175/WAF-D-11-00144.1.

Yair, Y., B. Lynn, C. Price, V. Kotroni, K. Lagouvardos, E. Morin, A. Mugnai, and M. d. C. Llasat (2010). Predicting the potential for lightning activity in Mediterranean storms based on the Weather Research and Forecasting (WRF) model dynamic and microphysical fields, J. Geophys. Res., 115, D04205, doi:10.1029/2008JD010868

How to cite: Yair, Y., Lynn, B., Ziv, B., and Yaffe, M.: Lightning super-bolts in Eastern Mediterranean winter thunderstorms, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-1788,, 2020.

EGU2020-13729 | Displays | NH1.3

Electrical characteristics and environmental conditions of lightning-ignited fires in the Iberian Peninsula and Mediterranean France between 2009 and 2015

Francisco J. Pérez-Invernón, Heidi Huntrieser, Sergio Soler Lopez, Francisco J. Gordillo-Vázquez, Javier Navarro-Gonzalez, Victor Reglero, Joan Montanyà, and Oscar A. van der Velde

About 5% of the wildfires in the Mediterranean basin are produced by lightning [1]. Lightning-ignited fires tend to occur in remote areas and can spread significantly before suppression. The occurrence of lightning-caused fires is closely related with intense drought periods and high temperatures [2]. Therefore, drier conditions and higher temperatures in a changing climate are expected to lead to a future increase in lightning-ignited fires occurrence. The development of a lightning-ignited fire parameterization for Earth system models arises as a necessary tool to predict the future occurrence of these extreme events and to study their impact on atmospheric chemistry.

Long Continuing Current lightning (LCC-lightning), preferable taking place in dry thunderstorms, is believed to be the main precursor of lightning-ignited fires. This was originally proposed by McEachron and Itagenguth in 1942 [3] working with laboratory sparks, which suggested that ignition by natural lightning is usually caused by a discharge having an unusual long-continuing current phase. Later in 1967 this hypothesis was confirmed by Fuquay et al. [4].

In this work, we analyse three fire databases of lightning-ignited fires in Spain, Portugal and Southern France between 2009 and 2015. Furthermore lightning measurements from the World Wide Lightning Location Network (WWLLN) and the Earth Networks Total Lightning Network (ENTLN), and land and atmospheric variables from the new ERA-5 reanalysis are combined to investigate the electrical characteristics and environmental conditions of the fires. This preliminary data analysis will be useful to set new relationships between the characteristics of thunderstorms and the initiation of wildfires. It is the first step towards the development of a detailed lightning-ignited fire parameterization for the atmospheric chemistry-climate model EMAC.

[1] Vázquez, A., and Moreno, J. M. (1998). Patterns of lightning-, and people-caused fires in peninsular Spain. International Journal of Wildland Fire, 8(2), 103-115.

[2] Pineda, N., and Rigo, T. (2017). The rainfall factor in lightning-ignited wildfires in Catalonia. Agricultural and Forest Meteorology, 239, 249-263.

[3] McEachron, K. B., and Itagenguth, J. It (1942), Effect of lightning on thin metal surfaces, AIEE Trans., 61, 559-564, 1942.

[4] Fuquay, D. M., Baughman R. G, Taylor, A. R. and Hawe, R. G. (1967). Characteristics of seven lightning discharges that caused forest fires. Journal of Geophysical Research, 72 (24).

How to cite: Pérez-Invernón, F. J., Huntrieser, H., Soler Lopez, S., Gordillo-Vázquez, F. J., Navarro-Gonzalez, J., Reglero, V., Montanyà, J., and van der Velde, O. A.: Electrical characteristics and environmental conditions of lightning-ignited fires in the Iberian Peninsula and Mediterranean France between 2009 and 2015, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-13729,, 2020.

EGU2020-10796 | Displays | NH1.3

Modelling dry thunderstorm environment during a wildfire episode in Portugal

Flavio T. Couto, Maksim Iakunin, Rui Salgado, Paulo Pinto, Tânia Viegas, and Jean-Pierre Pinty

Under future climate uncertainties, a better understanding of wildfires is necessary both from physical and operational points of view, which are the goals of the CILIFO (Centro Ibérico para la Investigacion y Lucha contra Incendios Forestales) Interreg POCTEP project. Among several sources of fire ignition, lightnings are the main natural source of wildfires and an important contributor to burned areas in many regions. In 2017, devastating forest fires were reported in Portugal. The fires near Pedrógão Grande created a huge wall of flames, killing at least 60 people. The goal of this study is to discuss the atmospheric conditions that were supportive of lightning flashes to cause a fire during this event, as well as to check the possibility to correctly diagnose cloud-to-ground flashes using high resolution simulations with the non-hydrostatic atmospheric Meso-NH model. A set of meteorological data was used to validate the model results and to describe the prevailing atmospheric environment during the afternoon of 17th June 2017 over central Portugal. The Portuguese Institute for Sea and Atmosphere (IPMA) provided the data for this study. The Meso-NH model was configured in order to provide an explicit representation of the clouds and their electrical activity, through the activation of the CELLS electrical scheme. The ICE3 microphysical scheme predicts the mixing ratio of six atmospheric water categories. The Meso-NH system also includes a grid point radar diagnostic given by the total equivalent radar reflectivity, as well as a Plan Position Indicator (PPI) that is a representation mode in which sweeping cones are projected on a horizontal plane determined by scanning the atmosphere at constant elevation. The description of the electrical state of a thunderstorm is based on the monitoring of the electrical charge densities, the computation of the electric field and the production of lightning flashes. The cloud charging involves mostly the non-inductive mechanism, and both Intra-Cloud (IC) and Cloud-to-Ground (CG) flashes are considered. The CELLS scheme provides a realistic representation of the electrical properties of precipitating cloud systems. The simulation was carried out with two nested domains of 4 km and 1 km horizontal resolution. Concerning the atmospheric conditions, the dry thunderstorm environment configured a perfect scenario for the natural ignition and evolution of some fires, since lightning activity came from high-base thunderstorms with relatively dry air at lower levels favouring the evaporation of rain before it reaches the ground, as well as intense outflows. Therefore, the fires on 17th June 2017 occurred in an exceptional hot day, with fire ignitions in places with complex terrain and a favourable vegetation state producing uncontrolled wildfires. The spatial distribution of the simulated CG lightnings showed a good agreement with the lightning strokes obtained from the national lightning detection network. Besides the identification of favourable conditions for the occurrence of wildfires, this study introduces a possible application of the Meso-NH electrical scheme, namely the study of forest fire ignition by lightning strokes.

How to cite: Couto, F. T., Iakunin, M., Salgado, R., Pinto, P., Viegas, T., and Pinty, J.-P.: Modelling dry thunderstorm environment during a wildfire episode in Portugal, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-10796,, 2020.

EGU2020-4872 | Displays | NH1.3

Schupy: a python package for modeling and analyzing Schumann resonances

Tamas Bozoki, Gabriella Satori, Erno Pracser, Jozsef Bor, Karolina Szabone Andre, Jesus Rodríguez-Camacho, Gergely Dalya, and Mariusz Neska

Schupy is an open-source python package aimed at modeling and analyzing Schumann resonances (SRs), the global electromagnetic resonances of the Earth-ionosphere cavity resonator in the lowest part of the extremely low frequency band (<100 Hz). Its very-first function forward_tdte applies the solution of the 2-D telegraph-equation introduced recently by Prácser et al. (2019) for a uniform cavity and is able to determine theoretical SR spectra for arbitrary source-observer configurations. It can be applied for modeling both the amplitude and phase of extraordinarily large SR-transients and the power spectral density of SRs excited by incoherently superimposed lightning strokes within an extended source region.

In this contribution, test results of planned new functionalities of the package are presented. A new function aims at removing sections of the measured data, e.g. Q-bursts, which bias spectral characteristics of  natural “background” electromagnetic noise. This way, PSD will be calculated from a sanitized time series. Other new functions are introduced for determining the spectral parameters (amplitude/intensity, frequency, Q-factor) of SR modes using different approaches, i.e., symmetrical and asymmetrical Lorentzian fitting, complex demodulation, and the weighted average method. We would like to encourage the community to join our project in developing open-source modeling and signal analyzing capacities for SR research as part of the schupy package.



How to cite: Bozoki, T., Satori, G., Pracser, E., Bor, J., Szabone Andre, K., Rodríguez-Camacho, J., Dalya, G., and Neska, M.: Schupy: a python package for modeling and analyzing Schumann resonances, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-4872,, 2020.

EGU2020-13501 | Displays | NH1.3

Comparison of global lightning activity variations inferred from Q-bursts, Schumann resonances, and WWLLN-detected lightning strokes

Karolina Szabóné André, József Bór, Gabriella Sátori, Tamás Bozóki, and Péter Steinbach

Measured time series of the extremely low frequency (ELF, 3 Hz-3 kHz) band electromagnetic field can be considered as a superposition of background and transient signals. Transient signals produced by exceptionally powerful lightning strokes far from the recording station are named Q-bursts. The direction of the source lightning stroke at the recording station can be calculated using the horizontal components of the Poynting vector. The source lightning stroke can be identified in the lightning database of the World Wide Lightning Location Network (WWLLN, by the matching detection time and direction calculated from ELF measurements.

Schumann resonance (SR) peaks appear at ~8Hz, ~14Hz, ~20 Hz, etc., in the spectra computed from the background ELF timeseries. SRs are natural electromagnetic resonances with wavelengths comparable to the circumference of the Earth-ionosphere waveguide. Peak amplitudes and frequencies in the resonance spectrum detected in the ELF band at any given location on the Earth depend on the distribution and intensity of the global lightning activity which excites SR.

ELF measurements are routinely performed in the Széchenyi István Geophysical Observatory (NCK, 47°38' N, 16°43' E) near Nagycenk, Hungary. Vertical electric and the horizontal magnetic components of the atmospheric electromagnetic field are monitored by the Schumann resonance recording system. In this work, we study the variation of the number of lightning strokes with high charge moment change (CMC; indicated by the number of large amplitude Q-bursts recorded at NCK) and the variation of the number of lightning strokes with large peak current (indicated by the number of WWLLN-detected energetic lightning strokes). In addition to considering the total number of WWLLN-detected lightning strokes and Q-bursts, we analyze lightning strokes occurring  only in west, south, east, and north directions from NCK, corresponding predominantly to the three main lightning producing regions of the tropical lands in America, Africa, and Indonesia as well as to the Pacific Ocean. Time variations of the number of high CMC and large peak current lightning strokes during November, 2014 are compared with time variation of the cumulative SR intensity detected at NCK station in the vertical electric field component in the same month. Similarities and differences in the time variations of the considered quantities are discussed in order to show how these indicators mirror the changing distributions of the global lightning activity.

How to cite: Szabóné André, K., Bór, J., Sátori, G., Bozóki, T., and Steinbach, P.: Comparison of global lightning activity variations inferred from Q-bursts, Schumann resonances, and WWLLN-detected lightning strokes, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-13501,, 2020.

EGU2020-21858 | Displays | NH1.3

Simultaneous detection of lightning flashes by MMIA-ASIM and Colombia Lightning Mapping Array

Jesús Alberto López, Joan Montanyà, Oscar van der Velde, Ferran Fabró, Javier Navarro, Víctor Reglero, Olivier Chanrion, Torsten Neubert, Krystallia Dimitriadou, and Nikolai Østgaard

Since April 2018, the Atmosphere-Space Interactions Monitor (ASIM) has been in operation on board the International Space Station (ISS). ASIM is composed of the Modular X-and Gamma Ray Sensor (MXGS) as well as a multispectral and high resolution array of photometers and cameras, called the Modular Multispectral Imaging Array (MMIA). These instruments allow us to investigate Terrestrial Gamma-Flashes, Transient Luminous Events and their interactions with thunderstorms and lightning flashes.

The Colombia Lightning Mapping Array (COL-LMA), operational since 2017, is the first VHF range network installed and working in a tropical region, and can contribute to the electrical understanding of thunderstorms and lightning leader processes associated with high energy phenomena in the upper atmosphere.

This work employs data from the MMIA array to investigate optical emission patterns at different bands (337 nm, 180-230 nm and 777.4 nm) caused by lightning leader development and cloud-to-ground flashes, derived from the COL-LMA and LINET network respectively. All cases are also correlated with optical observation from the Lightning Imaging Sensor (LIS) on board the ISS, and the Geostationary Lightning Mapper sensor on the GOES-R satellite.

The region of study is defined by the high detection-efficiency area of the COL-LMA around the Magdalena river valley. MMIA-ASIM information since July 2019 corresponding to passes over this tropical region has been analysed.

How to cite: López, J. A., Montanyà, J., van der Velde, O., Fabró, F., Navarro, J., Reglero, V., Chanrion, O., Neubert, T., Dimitriadou, K., and Østgaard, N.: Simultaneous detection of lightning flashes by MMIA-ASIM and Colombia Lightning Mapping Array, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-21858,, 2020.

A Mesoscale Convective System (MCS), consisting of three Super Cells
formed over South-east Indian, is assessed in detail with satellite and ground based
data-sets. The MCS under investigation generated a total of Ten (10) upward
electrical discharges (9 Sprites and 1 Gigantic Jet) commonly named as Transient
Luminous Events (TLEs). The TLEs were recorded from TLE observation station
located at Allahabad, India. The event occurred in the Post-Monsoon period of 2013
on October 7, during 15-23 UT hours. The MCS was spread over a region of 25000 sq.
Kilometers. A lowest cloud top temperature value of -84.7 0 C was observed in the
mature stage of the MCS, during 2130 UT hours, and the cloud top altitude was
reaching 17.6 km. The coldest cloud top region was covering an average area of
13000 sq. Km. The measured Convective Available Potential Energy (CAPE) value was
606.9 J/kg at 00 UT on 7 th October which dropped to 211 J/kg at 00 UT on 8 th
October. The mean lightning flash rate during the formation and maturity stages of
the MCS was around 46.03 min -1 . During the entire lifespan of the thunderstorm,
peak currents were found to be reaching ±400 kA. Such high electric currents,
extreme cold temperature and towering altitudes of the convective complexes show
how much a MCS is dynamically active and the TLEs which it produced are known to
electrically connect the lower atmosphere to the upper space environment.

How to cite: Moharana, S. S. and Singh, R.: Probing a post monsoon Mesoscale Convective System (MCS) and the generated Transient Luminous Events (TLEs) over Indian Region, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-19407,, 2020.

Using 5 years of operational Doppler radar, cloud-to-ground lightning observations and NECP reanalysis data, this study, for the first time for such a purpose, examines the spatial and temporal characteristics of and correlations between summer storm and lightning over the Yangtze-Huaihe River Basin (YHRB), with a special emphasize on their diurnal cycles. The sub-seasonal variability of the lifetime, storm top, max reflectivity and cell-based vertical integrated liquid (VIL) water of storms are also investigated using the Storm Cell Identification and Tracking algorithm. Results show that storms over YHRB occur most frequently during the Meiyu period. Storms are largely associated with Meiyu fronts during the period and show a fast-moving speed and moderate intensity (proxies including storms top, max reflectivity and VIL). The diurnal variations of storms embedded in Meiyu front are weak. The storm intensity becomes much stronger in the post-Meiyu period due to the increased atmospheric instability. Higher occurrence frequency of CG lighting can also be found during the post-Meiyu period. The diurnal cycles of storm and CG lightning in the post-Meiyu period show a unimodal pattern with an afternoon peak corresponding to solar heating effect. An inverse correlation between the lightning numbers and the mean value of peak current (MPC) for the negative CG lightning is found during the pre-Meiyu and Meiyu periods. The diurnal variation of MPC for the negative CG lightning agrees well with the storm intensity to some extent.

How to cite: Yang, J.: The diurnal cycle of lightning and storms during the pre-Meiyu, Meiyu and post-Meiyu period over Yangtze-Huaihe River Basin, China, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-12263,, 2020.

EGU2020-21927 | Displays | NH1.3

Relationship between aerosol concentration, relative humidity and atmospheric electric potential gradient in cities

Matthew Wright, James Matthews, Hugo Silva, Panida Navasumrit, Mathuros Ruchirawat, and Dudley Shallcross

The vertical atmospheric potential gradient is particularly affected by high aerosol loading in cities as the air’s conductivity is reduced through aerosol attachment of free ions. The reduction of ion concentrations decreases the conductivity and, as the air-earth current remains constant, the potential difference increases. Aerosol size distributions can be affected by the relative humidity dependent on the aerosol hygroscopicity, if an aerosol is sufficiently hygroscopic, it will grow as humidity increases. As larger aerosols are, in principle, more prone to effectively scavenge ions, an increase in relative humidity may increase the size of hygroscopic aerosols, decrease ion concentrations and hence increased measured potential gradient. Measurements of atmospheric potential gradient in Lisbon, Portugal, demonstrated an increase in potential gradient associated with increasing relative humidity (in the range 60-90%), mainly for wind directions corresponding to marine air.

A JCI 131 field mill (Chilworth) and Maximet 500 (Gill) weather station were positioned on the roof of the University of Bristol School of Chemistry between May and September 2016. Particle number concentration was determined using a condensation particle counter (TSI 3010) with an upper limit of 10,000 particles cm-3. A dilution system was put in place to increase this range to 14,000 cm-3. The same field mill and weather station were used in Thailand. Measurements at 1 Hz (averaged to 1-minute samples) were taken on the roof of a 6-floor building, approximately 100 m from a busy toll road in Lak Si, northern Bangkok. Aerosol concentrations were taken with a Condensation Particle Counter (Grimm Aerosol Technik) at the same height. The measurement period began on March 8th 2018 after which there were 8 weeks of particle number count data.

In the Bristol measurement between 50% and 80% relative humidity, the median potential gradient increased, but above this it sharply decreases, which may be due to disturbed weather at the highest humidities. Initial analysis of the relationship between relative humidity and potential gradient in Bangkok shows a decrease in median potential gradient as relative humidity increases. This may be due to a large proportion of traffic related aerosol which could be less hygroscopic, but the potential for effects of disturbed weather and traffic to mask hygroscopic effects will be considered.

How to cite: Wright, M., Matthews, J., Silva, H., Navasumrit, P., Ruchirawat, M., and Shallcross, D.: Relationship between aerosol concentration, relative humidity and atmospheric electric potential gradient in cities , EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-21927,, 2020.