Predicting current and future flood risk continues to be a major challenge for climatologists, hydrologists and hydraulicians. The complex nature of flood risk challenges established risk assessment methodologies and their modelling components, such as hydrologic and hydraulic simulation. Further, flood risk assessment is characterised by considerable uncertainty, which needs to be evaluated and clearly communicated to decision-makers.
This session aims to review state-of-the-art flood hazard, damage, and risk assessment methodologies on different scales from the building scale to the global level, as well as experiences of recent flood events, the physical processes occurring during flood flows, and uncertainties in measurement data and modelling. We welcome submissions in the areas of flood plain and urban risk assessment and uncertainty analysis, flood management including new approaches to hydraulic modelling, model calibration and validation and flood damage estimation.
Also, we are interested in contributions that show what kind of information is particularly helpful for reducing uncertainty, as well as measures for flood mitigation and the cost effectiveness of these measures. Abstracts are sought from those involved in both the theoretical and practical aspects related to these topics.

Worldwide, the frequency and magnitude of extreme flooding are steadily increasing, causing considerable losses of life and property. It hampers well-being and economic growth in many countries, so that flood forecasting and flood risk assessment have become of upmost importance. New and rapidly developing techniques are becoming widespread, such as unmanned aerial vehicles (UAV), synthetic-aperture radar (SAR) or satellite-based systems. Combined with fit-for-purpose hydrodynamic models, these techniques pave the way for breakthroughs in flood assessment and flood risk management. This provides a unique platform for the scientific community to explore the driving mechanisms of flood risk and to build up efficient strategies for flood mitigation and enhancing flood resilience.
This session invites presentations on research based on high-resolution aerial and satellite techniques like UAV, SAR, Altimeter, SCATSAT-1, etc. for flood monitoring, including mapping of inundation extent, flow depths, velocity fields, flood-induced morphodynamics, debris transport. It also invites the presentation of innovative modelling techniques of flood hydrodynamics, flood hazard, damage and risk assessment, as well as flood relief prioritization, dam and dike(levees) break floods, and flood mitigation strategies. Studies dealing with the modelling uncertainties and modern techniques for model calibration and validation are particularly welcome.
Furthermore, real-time flood inundation mapping is critical aspect for the evacuation of people from low-lying areas and to reduce casualties. Acquisition of real-time data gained through UAV-based flood inundation mapping and modelling, as well as assessment of uncertainties in real-time aerial surveying are welcome in this session.

Invited speaker:
Frederik Kratzert.
Mr Kratzert holds a MSc in environmental engineering with focus on hydrology and is now doing a PhD in Machine Learning at the Johannes Kepler University, Linz, Austria under the supervision of Sepp Hochreiter. His research is focused around the use of the LSTM neural network for hydrological/environmental modeling and his PhD is funded by Google AI.

Lightning is the energetic manifestation of electrical breakdown, occurring after charge separation processes operating on micro and macro-scales, leading to strong electric fields within thunderstorms. Lightning is associated with severe weather, torrential rains and flash floods. It has significant effects on various atmospheric layers and drives the fair-weather electric field. It is a strong indicator of convective processes on regional and global scales, potentially associated with climate change. Thunderstorms and lightning are also associated to the production of energetic radiation up to tens of MeV on time scales from sub-millisecond (Terrestrial Gamma-ray Flashes) to tens of seconds (gamma-ray glows).

This session seeks contributions from research in atmospheric electricity on:

Atmospheric electricity in fair weather and the global electrical circuit
Atmospheric chemical effects of lightning and Lightning-produced NOx
Middle atmospheric Transient Luminous Events
Energetic radiation from thunderstorms and lightning
Remote sensing of lightning from space and by lightning detection networks
Results from the Atmosphere-Space Interaction Monitor (ASIM) mission.
Thunderstorms, flash floods and severe weather
Lightning and electrical phenomena on other planets
Lightning, tropical storms and climate
Modeling of thunderstorms and lightning
Now-casting and forecasting of thunderstorms
Laboratory investigation of lightning discharge physics processes

In many parts of the world, weather represents one of the major uncertainties affecting performance and management of agricultural systems. Due to global climate changes the climatic variability and the occurrence of extreme weather events is likely to increase leading to substantial increase in agricultural risk and destabilisation of farm incomes. This issue is not only important for farm managers but also for policy makers, since income stabilisation in agriculture is frequently considered as a governmental task.

The aim of this session is to discuss the state of the art research in the area of analysis and management of weather-related risks in agriculture. Both structural and non-structural measures can be used to reduce the impact of climate variability including extreme weather on crop production. While the structural measures include strategies such as irrigation, water harvesting, windbreaks etc., the non-structural measures include the use of the medium-range weather forecast and crop insurance.

The topic is at the borderline of different disciplines, in particular agricultural and financial economics, meteorology, modelling and agronomy. Thus, the session offers a platform to exchange ideas and views on weather-related risks across these disciplines with the focus on quantifying the impact of extreme weather on agricultural production including impacts of climate change, analysis of financial instruments that allow reducing or sharing weather-related risks, evaluation of risk management strategies on the farm level, development of the theory of risk management and to exchange practical experiences with the different types of weather insurance.

This session has been promoted by:
• Natural hazard Early career scientists Team (NhET, https://blogs.egu.eu/divisions/nh/tag/early-career-scientists/)
• Boosting Agricultural Insurance based on Earth Observation data (BEACON, https://beacon-h2020.com/)
• Research Center for the Management of Agriculutral and Environmental Risks (CEIGRAM, http://www.ceigram.upm.es/ingles/)

Severe hydro-meteorological phenomena (i.e. extreme weather in terms of precipitation, heat waves and wind storms) on land and sea have a high impact globally as well as in European territories. The increasing frequency and severity of hydro-meteorological events such as hurricanes, intense cyclones, or destructive thunderstorms appear to be associated with climate change and an increasing number of people is exposed to climate-related hazards each year – particularly the most vulnerable. The science behind these phenomena is complex, but advancement in evidence-based knowledge, together with progress in technology and data-driven measurement systems, allow more detailed monitoring and forecasting capability to target interventions at the appropriate time-scale. The employment of nature-based solutions (NBS) to mitigate the impact of hydro-meteorological phenomena could be a viable approach requiring coordinated efforts.
The session intends to stimulate the international scientific community across several fields to demonstrate how nature-based solutions (NBSs) could contribute to disaster risk reduction in line with the EU Roadmap for achieving the goals of the Sendai Framework. It aims to promote and share experience with the best available science and knowledge to establish a coherent approach towards risk mitigation. Results from the EU H2020 projects NAIAD, OPERANDUM, PHUSICOS and RECONECT are encouraged as well as contributions discussing the main drivers and barriers for NBSs implementation . Also contributions documenting how NBS can be beneficial in land use planning, risk assessment, climate change impact, disaster prevention are welcome.
Specific topics are related to the following questions
- How can we mainstream the adoption of innovative, systemic and locally-attuned nature-based solutions for hydro-meteorological risk reduction at watershed/landscape scale? - What are the required features of comprehensive framework for comparing green and blue/grey/hybrid hydro-meteorological risk prevention and reduction solutions? - What is the evidence on the effectiveness of these solutions? How can we capture the potential (insurance) value of ecosystems?
Additional topics are
- Methods for NBS co-designing and co-development - Methods for the identification and assessment of barriers related to social and cultural acceptance and in regulatory frameworks that hinder the adoption of NBS.

Public information:
Dear Authors,

you are kindly invited to upload material by May 3, 2020. All accepted abstracts will be discussed. We reccommend 3-5 sharp slides with aim - methods - main results and conclusions. We are very excited to hear about your work and findings.
Best regards,
Silvana, Amy, Elena and Zoran

Today, it is almost certain that global climate change will affect the frequency and severity of extreme meteorological and hydrological events. It is necessary to develop models and methodologies for the better understanding, forecasting, hazard prevention of weather induced extreme events and assessment of disaster risk. This session considers extreme events that lead to disastrous hazards induced by severe weather and climate change. These can, e.g., be tropical or extratropical rain- and wind-storms, hail, tornadoes or lightning events, but also floods, long-lasting periods of drought, periods of extremely high or of extremely low temperatures, etc. Papers are sought which contribute to the understanding of their occurrence (conditions and meteorological development), to assessment of their risk and their future changes, to the ability of models to reproduce them and methods to forecast them or produce early warnings, to proactive planning focusing to damage prevention and damage reduction. Papers are also encouraged that look at complex extreme events produced by combinations of factors that are not extreme by themselves. The session serves as a forum for the interdisciplinary exchange of research approaches and results, involving meteorology, hydrology, hazard management and/or applications like insurance issues.

Public information:
NH1.6/AS1.5/HS13.10

Extreme meteorological and hydrological events induced by severe weather and climate change
Display presentations Monday, 04 May, 08:30–12:30

The presentation of Displays during the chat will be made in the following order:

Severe storms/precipitation (8:30-10:15): D1932, D1933, D1934, D1936, D1938, D1940, D1942, D1943, D1944, D1951, D1952, D1953, D1955, D1956, D1957, D1958, D1960, D1962, D1963 (not presented), D1964, D1965, D1966, D1967, D1969, D1974, D1977, D1982

Floods (10:45-11:05): D1935, D1937, D1939, D1941, D1954, D1959

Droughts and other extreme weather events (11:05-12:30): D1945, D1946, D1947, D1948, D1949, D1950, D1961, D1968 (not presented), D1970, D1971, D1972, D1973 (not presented), D1975, D1976, D1977, D1978, D1979, D1980, D1981, D1983, D1984, D1985

Information (video and text) how to use the chats could be found at https://egu2020.eu/sharing_geoscience_online/how_to_use_the_chats.html

The chairpersons will handle and organize the questions and replies of the presentations, following the above line of presentations. Each author is asked for an introduction (please prepare). Then, we will take questions.

Conveners, co-conveners, and chairpersons of the sessions reserve the right to ban participants showing abusive behaviour or violating EGU's Code of Conduct.

The conveners of the session
Athanasios Loukas
Maria Carmen Llasat
Uwe Ulbrich

Heavy precipitation events in small and medium size catchments can trigger flash floods, which are characterized by very short response times and high specific peak discharges, and often occur in ungauged basins. Under appropriate geomorphological conditions, such rainstorms also cause debris flows or shallow landslides mobilizing large amounts of unconsolidated material. Although significant progress has been made in the management of these different hazards and related risks, they remain poorly understood and their predictability is affected by large uncertainties, due to the fast evolution of triggering rainfall events, the lack of appropriate observations, the high variabilities and non-linearities in the physical processes, and the high variability and complexity of societal vulnerability.

This session aims to illustrate current advances in monitoring, understanding, modelling, and forecasting flash floods and associated geomorphic processes, and documenting and anticipating the societal impacts and social responses.

Contributions on the following scientific themes are more specifically expected:
- Development of new measurement techniques adapted to flash floods monitoring (including remote sensing data, weather radar, and lightning), and quantification of the associated uncertainties,
- Identification of processes leading to flash flood events and/or rainfall-induced geomorphic hazards from data analysis and/or modelling, and of their characteristic space-time scales
- Possible evolutions in hazard characteristics and frequency related to climate change.
- Development of short-range (0-6h) rainfall forecasting techniques adapted to heavy precipitation events, and representation of associated uncertainties
- Development of hydro-meteorological forecasting chains for predicting flash floods and/or rainfall-induced geomorphic hazards in gauged and ungauged basins
- Development of inundation mapping approaches specifically designed for an integration in flash floods forecasting chains.
- Use of new criteria such as specific “hydrological signatures” for model and forecast evaluation
- Observation, understanding and prediction of the societal vulnerability and social responses to flash floods and/or associated hydro-geomorphic hazards.

Hydroinformatics has emerged over the last decades to become a recognised and established field of independent research within the hydrological sciences. Hydroinformatics is concerned with the development and hydrological application of mathematical modelling, information technology, systems science and computational intelligence tools. We also have to face the challenges of Big Data: large data sets, both in size and complexity. Methods and technologies for data handling, visualization and knowledge acquisition are more and more often referred to as Data Science.

The aim of this session is to provide an active forum in which to demonstrate and discuss the integration and appropriate application of emergent computational technologies in a hydrological modelling context. Topics of interest are expected to cover a broad spectrum of theoretical and practical activities that would be of interest to hydro-scientists and water-engineers. The main topics will address the following classes of methods and technologies:

* Predictive and analytical models based on the methods of statistics, computational intelligence, machine learning and data science: neural networks, fuzzy systems, genetic programming, cellular automata, chaos theory, etc.
* Methods for the analysis of complex data sets, including remote sensing data: principal and independent component analysis, time series analysis, information theory, etc.
* Specific concepts and methods of Big Data and Data Science
* Optimisation methods associated with heuristic search procedures: various types of genetic and evolutionary algorithms, randomised and adaptive search, etc.
* Applications of systems analysis and optimisation in water resources
* Hybrid modelling involving different types of models both process-based and data-driven, combination of models (multi-models), etc.
* Data assimilation and model reduction in integrated modelling
* Novel methods of analysing model uncertainty and sensitivity
* Software architectures for linking different types of models and data sources

Applications could belong to any area of hydrology or water resources: rainfall-runoff modelling, flow forecasting, sedimentation modelling, analysis of meteorological and hydrologic data sets, linkages between numerical weather prediction and hydrologic models, model calibration, model uncertainty, optimisation of water resources, etc.

The hydrological response to precipitation at the catchment scale is the result of the interplay between the space-time variability of precipitation, the catchment geomorphological / pedological / ecological characteristics and antecedent hydrological conditions. Therefore, (1) accurate measurement and prediction of the spatial and temporal distribution of precipitation over a catchment and (2) the efficient and appropriate description of the catchment properties are important issues in hydrology. This session focuses on the following aspects of the space-time variability of precipitation:
- Novel techniques for measuring liquid and solid precipitation at hydrologically relevant space and time scales, from in situ measurements to remote sensing techniques, and from ground-based devices to spaceborne platforms.
- Novel approaches to better identify, understand and simulate the dominant microphysical processes at work in liquid and solid precipitation.
- Applications of measured and/or modelled precipitation fields in catchment hydrological models for the purpose of process understanding or predicting hydrological response.

Hydro-meteorological extremes such as floods, droughts, storms, or heatwaves often affect large regions therefore causing large damages and costs. Hazard and risk assessments, aiming at reducing the negative consequences of such extreme events, are often performed with a focus on one location despite the spatial nature of extreme events. While spatial extremes receive a lot of attention by the media, little is known about their driving factors and it remains challenging to assess their risk by modelling approaches. Key challenges in advancing our understanding of spatial extremes and in developing new modeling approaches include the definition of multivariate events, the quantification of spatial dependence, the dealing with large dimensions, the introduction of flexible dependence structures, the estimation of their probability of occurrence, the identification of potential drivers for spatial dependence, and linking different spatial scales. This session invites contributions which help to better understand processes governing spatial extremes and/or propose new ways of describing and modeling spatial extremes at different spatial scales.

Target audience: hydrologists, climatologists, statisticians, machine learners, and researchers interested in spatial risk assessments.

The assessment of precipitation variability and uncertainty is crucial in a variety of applications, such as flood risk forecasting, water resource assessments, evaluation of the hydrological impacts of climate change, determination of design floods, and hydrological modelling in general. Within this framework, this session aims to gather contributions on research, advanced applications, and future needs in the understanding and modelling of precipitation variability, and its sources of uncertainty.
Specifically, contributions focusing on one or more of the following issues are particularly welcome:
- Novel studies aimed at the assessment and representation of different sources of uncertainty versus natural variability of precipitation.
- Methods to account for different accuracy in precipitation time series, e.g. due to change and improvement of observation networks.
- Uncertainty and variability in spatially and temporally heterogeneous multi-source precipitation products.
- Estimation of precipitation variability and uncertainty at ungauged sites.
- Precipitation data assimilation.
- Process conceptualization and modelling approaches at different spatial and temporal scales, including model parameter identification and calibration, and sensitivity analyses to parameterization and scales of process representation.
- Modelling approaches based on ensemble simulations and methods for synthetic representation of precipitation variability and uncertainty.
- Scaling and scale invariance properties of precipitation fields in space and/or in time.
- Physically and statistically based approaches to downscale information from meteorological and climate models to spatial and temporal scales useful for hydrological modelling and applications.

Urban hydrological processes are characterized by high spatial variability and short response times resulting from a high degree of imperviousness. Therefore, urban catchments are especially sensitive to space-time variability of precipitation at small scales. High-resolution precipitation measurements in cities are crucial to properly describe and analyses urban hydrological response. At the same time, urban landscapes pose specific challenges to obtaining representative precipitation and hydrological observations.

This session focuses on high-resolution precipitation and hydrological measurements in cities and on approaches to improve modeling of urban hydrological response, including:

- Novel techniques for high-resolution precipitation measurement in cities and for multi-sensor data merging to improve the representation of urban precipitation fields.
- Novel approaches to hydrological field measurements in cities, including data obtained from citizen observatories.
- Precipitation modeling for urban applications, including convective permitting models and stochastic rainfall generators.
- Novel approaches to modeling urban catchment properties and hydrological response, from physics-based, conceptual and data-driven models to stochastic and statistical conceptualization.
- Applications of measured precipitation fields to urban hydrological models to improve hydrological prediction at different time horizons to ultimately enable improved management of urban drainage systems (including catchment strategy development, flood forecasting and management, real-time control and proactive protection strategies aimed at preventing flooding and pollution).
- Strategies to deal with upcoming challenges, including climate change and rapid urbanization.

Earth Systems Models aim at describing the full water- and energy cycles, i.e. from the deep ocean or groundwater across the sea or land surface to the top of the atmosphere. The objective of the session is to create a valuable opportunity for interdisciplinary exchange of ideas and experiences among members of the Earth System modeling community and especially atmospheric-hydrological modelers.
Contributions are invited dealing with approaches how to capture the complex fluxes and interactions between surface water, groundwater, land surface processes, oceans and regional climate. This includes the development and application of one-way or fully-coupled hydrometeorological prediction systems for e.g. floods, droughts and water resources at various scales. We are interested in model systems that make use of innovative upscaling and downscaling schemes for predictions across various spatial- and temporal scales. Contributions on novel one-way and fully-coupled modeling systems and combined dynamical-statistical approaches are encouraged. A particular focus of the session is on weakly and strongly coupled data assimilation across the different compartments of the Earth system for the improved prediction of states and fluxes of water and energy. Merging of different observation types and observations at different length scales is addressed as well as different data assimilation approaches for the atmosphere-land system, the land surface-subsurface system and the atmosphere-ocean system. The value of different measurement types for the predictions of states and fluxes, and the additional value of measurements to update states across compartments is of high interest to the session. We also encourage contributions on use of field experiments and testbeds equipped with complex sensors and measurement systems allowing compartment-crossing and multi-variable validation of Earth System Models.

River monitoring remains a challenge for hydrologists and environmental agencies. The expansion of the human population, urbanisation, technological advancements and a changing global climate have put forward an ongoing water management agenda. River streamflow is one of the most crucial hydrological variables in terms of 'basin health' description (from an ecological point of view), and for flood risk management and modelling. However, despite significant efforts on river flow monitoring, long-term, spatially dense monitoring networks remain scarce, stressing the need for innovative solutions dealing with the twin challenges of a changing climate. Emerging innovative methods should be tested and benchmarked under different flow conditions to ensure accurate and consistent results and well-understood measurement uncertainties. Furthermore, these methods must be harmonised for promoting good practices and dissemination over the globe. In this context, this session focuses on:

1) The use of remote sensing approaches for hydrological and morphological monitoring;
2) Real-time acquisition of hydrological variables;
3) Innovative methodologies for measuring/modelling/estimating river stream flows;
4) Measuring the extremes of high and low flows associated with a changing climate;
5) Strategies to quantify and describe hydro-morphological evolution of rivers;
6) New methods to cope with data-scarce environments;
7) Inter-comparison of innovative and classical models and approaches;
8) Quantification of uncertainties; and,
9) Guidelines for hydro-morphological streamflow monitoring.

Contributions are welcome with emphasis on image-velocimetry or other velocity measurement techniques, wetted cross-section retrieval from digital surface models (e.g. computed with multi-media photogrammetry/structure-from-motion, or other bathymetric techniques), and quantification of stream flows and related uncertainties. Additionally, presentations of case studies using innovative sensors, Unmanned Aerial Systems (UASs) and Unmanned Surface Vehicles (USVs), airborne or satellite-based approaches, and traditional in-situ measurements are encouraged. This session is sponsored by the COST Action CA16219, Harmonisation of UAS techniques for agricultural and natural ecosystems monitoring (HARMONIOUS).
Note: This session is complemented by a field-based short-course, SC2.9, offering attendees the opportunity to experience some of these tools and techniques in a river environment.

Karst environments are characterized by distinctive landforms and unique hydrologic behaviors. Karst systems are commonly extremely complex, heterogeneous, and very difficult to manage because their formation and evolution are controlled by a wide range of geological, hydrological, geochemical and biological processes. Further, karst systems are extremely vulnerable due to the direct connection between the surface and subsurface compartments through conduit networks. The great variability and unique connectivity may result in serious engineering problems: on one hand, karst groundwater resources are readily contaminated by pollution because of the rapidity of conduit flow; on the other hand, the presence of karst conduits that weakens the strength of the rock mass may lead to serious natural and human-induced hazards. The plan and development of engineering projects in karst environments thus require: 1) an enhanced understanding of natural processes that govern the initiation and
evolution of karst systems through both field and modelling approaches, and 2) specific interdisciplinary approaches aiming at better assessing the associated uncertainties and minimizing the detrimental effects of hazardous processes and environmental problems.
This session calls for abstracts on research related to geomorphology, hydrogeology, engineering geology, and/or hazard mitigation in karst environments in the context of climate change and increased human disturbance. It also aims to discuss various characterization and modelling methods applied in each specific
research domain, with their consequences on the understanding of the whole process of karst genesis and functioning.

This PICO session addresses three sub-topics :

Precipitation variability: from drop scale to lot scale:
The understanding of small scale (sec – drop scale to min -km) spatio-temporal variability of precipitation is essential for larger scale studies, especially in highly heterogeneous areas (mountains, cities). Nevertheless grasping this variability remains an open challenge. An illustration of the range of scales involved is the ratio between the effective sampling areas of point measurement devices (rain gauges and disdrometers) and weather radars, which is greater than 10^7! This session aims at bridging this scale gap and improving the understanding of small scale precipitation variability, both liquid and solid, as well as its hydro-meteorological consequences at larger scales.

Hydroclimatic and hydrometeorologic stochastics: Extremes, scales, probabilities:
The departure of statistical properties of hydrometeorological processes from the classical statistical prototype has been established. This session aims at presenting the latest developments on:
- Coupling stochastic approaches with deterministic hydrometeorological predictions;
- Stochastic-dynamic approaches;
- Variability at climatic scales and its interplay with the ergodicity of space-time probabilities;
- Linking underlying physics and scaling stochastics of hydrometeorological extremes;
- Development of parsimonious representations of probability distributions of hydrometeorological extremes over a wide range of scales and states; as well as their applications in risk analysis and hazard predictions
The session is co-sponsored by the ICSH-IAHS, former STAHY.

The atmospheric water cycle under change: feedbacks, land use, hydrological changes and implications :
Traditionally, hydrologists have always considered precipitation and temperature as input to their models and evaporation as a loss. However, more than half of the evaporation globally comes back as precipitation on land. Anthropogenic pressure through land-use changes (and greenhouse gasses) alter, not only, the local hydrology, but through atmospheric water and energy feedbacks also effect the water cycle in remote locations. This session aims to:
- investigate the remote and local atmospheric feedbacks from human interventions, based on observations and coupled modelling approaches.
- explore the implications of atmospheric feedbacks on the hydrologic cycle for land and water management (ex. changing land cover)

Geostatistics is commonly applied in the Water, Earth and Environmental sciences to quantify spatial variation, produce interpolated maps with quantified uncertainty and optimize spatial sampling designs. Extensions to the space-time domain are also a topic of current interest. Due to technological advances and abundance of new data sources from remote and proximal sensing and a multitude of environmental sensor networks, big data analysis and data fusion techniques have become a major topic of research. Furthermore, methodological advances, such as hierarchical Bayesian modeling and machine learning, have enriched the modelling approaches typically used in geostatistics.

Earth-science data have spatial and temporal features that contain important information about the underlying processes. The development and application of innovative space-time geostatistical methods helps to better understand and quantify the relationship between the magnitude and the probability of occurrence of these events.

This session aims to provide a platform for geostatisticians, soil scientists, hydrologists, earth and environmental scientists to present and discuss innovative geostatistical methods to study and solve major problems in the Water, Earth and Environmental sciences. In addition to methodological innovations, we also encourage contributions on real-world applications of state-of-the-art geostatistical methods.

Given the broad scope of this session, the topics of interest include the following non-exclusive list of subjects:
1. Advanced parametric and non-parametric spatial estimation and prediction techniques
2. Big spatial data: analysis and visualization
3. Optimisation of spatial sampling frameworks and space-time monitoring designs
4. Algorithms and applications on Earth Observation Systems
5. Data Fusion, mining and information analysis
6. Integration of geostatistics with optimization and machine learning approaches
7. Application of covariance functions and copulas in the identification of spatio-temporal relationships
8. Geostatistical characterization of uncertainties and error propagation
9. Bayesian geostatistical analysis and hierarchical modelling
10. Functional data analysis approaches to geostatistics
11. Geostatistical analysis of spatial compositional data
12. Multiple point geostatistics
13. Upscaling and downscaling techniques
14. Ontological framework for characterizing environmental processes

In the current context of global change, assessing the impact of climate variability and changes on hydrological systems and water resources is increasingly crucial for society to better-adapt to future shifts in water resources as well as extreme conditions (floods and droughts). However, hitherto, important sources of uncertainties have been neglected in forecasting climate impacts on hydrological systems, especially uncertainties associated with internal/natural climate variability, whose contribution to near-future changes could be as important as forced anthropogenic climate changes at the regional scales. Internal climate modes of variability (e.g. ENSO, NAO, AMO) and their impact on the continent are not properly reproduced in the current global climate models, leading to large underestimations of decadal climate and hydroclimatic variability at the global scale. At the same time, hydrological response strongly depends on catchment properties, whose interactions with climate variability are little understood at the decadal timescales. These factors altogether reduce significantly our ability to understand long-term hydrological variability and to improve projection and reconstruction of future and past hydrological changes on which improvement of adaption scenarios depends.
We welcome abstracts capturing recent insights for understanding past or future impacts of large-scale climate variability on hydrological systems and water resources as well as newly developed projection and reconstruction scenarios. Results from model intercomparison studies are encouraged.

Public information:
Dear all,

We hope that you are all well, and ready to participate to the EGU 2020 “sharing geoscience online”.
Our session "HS2.4.6/CL2.29/NH1.21: Understanding the links between hydrological variability and internal/natural climate variability" is scheduled tomorrow (Thursday 07) at 10:45-12:30 (CET time).
As you might have noticed in the last days, chairing the online chat requires some managements. With the convener team, we therefore agreed on an organisation plan to enable everyone to present their displays, and discuss it smoothly with the session participants.

First, we would appreciate if you could upload your presentation materials as soon as possible. Because there is not much time per presentation in the chats, participants are reviewing materials in advance of the scheduled sessions, in order to maximise discussion time.

If the first author of your display will not be available, we request that you let us know in advance, who is attending, so we can be sure all expected presenters are online.

When posting your questions, as well as replying, we recommend you begin your questions/answers with @1stAuthorName (e.g. in my case @Bastien). This will make sure that the question/answer is addressed to the right correspondent.

Below are some information on the conduct of our session:

i) We will go through ONLY the presentations which have uploaded materials for displays, and we will follow the order provided on the session programme;

ii) After a brief introduction, we will give 10 minutes to all participants to look through the different displays;

iii) We will then call each author, who will have 2-3 minutes to tell us about their work. As this is not that easy, we strongly recommend you to prepare few highlights (context + bullet points; max. 6 sentences) in advance. So, you can just paste it at the time.

iv) We then will allow 2-3 minutes for questions to each author. Again, we recommend you to prepare any questions for the other authors in advance.

v) Finally, we will thank all the participants, and call for online comments on the website.
We hope to “see” you tomorrow morning, and we hope this will be a nice experience for everyone.

To help with this, we would appreciate if you could upload your material as soon as you can. Bear in mind that it can be updated at anytime.

Note that the time allocated to the presentation and questions might have to be adjusted tomorrow, depending on the final number of displays

Best Regards,
Bastien, Jean-Philippe, Katie and Nicolas

Mountains cover approximately one quarter of the total land surface on the planet, and a significant fraction of the world’s population lives in their vicinity. Orography critically affects weather and climate processes at all scales and, in connection with factors such as land-cover heterogeneity, is responsible for high spatial variability in mountain weather and climate.

Due to this high complexity, monitoring and modeling the atmosphere and the other components of the climate system in mountain regions is challenging both at short (meteorological) and long (climatological) time-scales. This session is devoted to the better understanding of weather and climate processes in mountain and high-elevation areas around the globe, as well as their modification induced by global environmental change.

We welcome contributions describing the influence of mountains on the atmosphere on meteorological time-scales, including terrain-induced airflow, orographic precipitation, land-atmosphere exchange over mountains, forecasting and predictability of mountain weather. Furthermore we invite studies that investigate climate processes and climate change in mountain areas and its impacts on dependent systems, based on monitoring and modeling activities. Particularly welcome are contributions that merge various sources of information and reach across disciplinary borders (atmospheric, hydrological, cryospheric, ecological and social sciences). In this respect the session invites also contributions on outcomes of the WMO "High Mountain Summit" taking place in October 2019.

Public information:
Online survey (including questions about a possible follow-up webinar): https://form.jotformeu.com/83462227858365

The understanding of tropical phenomena and their representation in numerical models still raise important scientific and technical questions, particularly in the coupling between the dynamics and diabatic processes. Among these phenomena, tropical cyclones (TC) are of critical interest because of their societal impacts and because of uncertainties in how their characteristics (cyclogenesis processes, occurrence, intensity, latitudinal extension, translation speed) will change in the framework of global climate change. The monitoring of TCs, their forecasts at short to medium ranges, and the prediction of TC activity at extended range (15-30 days) and seasonal range are also of great societal interest.

The aim of the session is to promote discussions between scientists focusing on the physics and dynamics of tropical phenomena. This session is thus open to contributions on all aspects of tropical meteorology between the convective and planetary scale, such as:

- Tropical cyclones,
- Convective organisation,
- Diurnal variations,
- Local circulations (i.e. island, see-breeze, etc.),
- Monsoon depressions,
- Equatorial waves and other synoptic waves (African easterly waves, etc.),
- The Madden-Julian oscillation,
- etc.

We especially encourage contributions of observational analyses and modelling studies of tropical cyclones and other synoptic-scale tropical disturbances including the physics and dynamics of their formation, structure, and intensity, and mechanisms of variability of these disturbances on intraseasonal to interannual and climate time scales.

Findings from recent field campaigns such as YMC and PISTON are also encouraged.

This session investigates mid-latitude cyclones and storms on both hemispheres. We invite studies considering cyclones in different stages of their life cycles from the initial development, to large- and synoptic-scale conditions influencing their growth to a severe storm, up to their dissipation and related socioeconomic impacts.
Papers are welcome, which focus also on the diagnostic of observed past and recent trends, as well as on future storm development under changed climate conditions. This will include storm predictability studies on different scales. Finally, the session will also invite studies investigating impacts related to storms: Papers are welcome dealing with vulnerability, diagnostics of sensitive social and infrastructural categories and affected areas of risk for property damages. Which risk transfer mechanisms are currently used, depending on insured and economic losses? Which mechanisms (e.g. new reinsurance products) are already implemented or will be developed in order to adapt to future loss expectations?

As the societal impacts of hazardous weather and other environmental pressures grow, the need for integrated predictions which can represent the numerous feedbacks and linkages between physical and chemical atmospheric processes is greater than ever. This has led to development of a new generation of high resolution multi-scale coupled prediction tools to represent the two-way interactions between aerosols, chemical composition, meteorological processes such as radiation and cloud microphysics.
Contributions are invited on different aspects of integrated model and data assimilation development, evaluation and understanding. A number of application areas of new integrated modelling developments are expected to be considered, including:
i) improved numerical weather prediction and chemical weather forecasting with feedbacks between aerosols, chemistry and meteorology,
ii) two-way interactions between atmospheric composition and climate variability.
This session aims to share experience and best practice in integrated prediction, including:
a) strategy and framework for online integrated meteorology-chemistry modelling;
b) progress on design and development of seamless coupled prediction systems;
c) improved parameterisation of weather-composition feedbacks;
d) data assimilation developments;
e) evaluation, validation, and applications of integrated systems.
This Section is organised in cooperation with the Copernicus Atmosphere Monitoring Service (CAMS) and the WMO Global Atmosphere Watch (GAW) Programme.
This year session is dedicated to the Global Air Quality Forecasting and Information Systems (GAFIS) - a new initiative of WMO and several international organizations - to enable and provide science-based air quality forecasting and information services in a globally harmonized and standardized way tailored to the needs of society.

In recent years, attention was paid to the detection and monitoring of volcanic ash clouds as their impact on the air traffic control system was unprecedented. Volcanic clouds are dangerous for the aviation as they can cause damage of the aircraft systems and engines not only close to active volcanoes but also at large distance from the eruption.
The intensity of the extreme convective events is supposed to increase worldwide due to the climate change and they can also cause large damages and affect air safety.

The recent Anak Krakatau, Raikoke and Ulawun eruptions highlighted the issue on different techniques to distinguish volcanic ash clouds from convective clouds, and the unsolved problem to understand if the cloud top is tropospheric or stratospheric.

The “extreme clouds” detection and estimation of their physical parameters is a highly multidisciplinary and challenging topic since the same techniques and instruments can be used for meteorology, volcanic monitoring, atmospheric physics and climate purposes. There is an urgent need to develop new techniques and instruments for monitoring, detecting and modeling “extreme clouds” to develop early warning systems and to support users, decision makers and policy makers.

This session solicits the latest studies from the spectrum of:
- Volcanic and Convective Clouds (CVC) remote sensing, detection, monitoring, modeling, forecasting and nowcasting
- understanding of CVC structure, including overshooting and ice clouds
- understanding the impact of CVC on climate changes and air safety
- proposal of new products or services focused on the end-users prospective (air traffic management and air safety)
- discussion on the recent Anak Krakatau, Raikoke and Ulawun eruptions

By considering studies over this range of topics we aim to identify new methods, detail current challenges, understand common techniques/methods and identify common discussions within the communities of atmospheric physicists, meteorologists, modelers, air traffic managers, pilots sensors engineers and engines manufacturers.

We particularly welcome and encourage contributions connecting different fields such as:
- forecasting tools to support air traffic management improving the limits of the present science and new products/tools providing better services to the end-users,
- extreme clouds remote sensing with novel techniques and new sensors,
- novel techniques to detect overshooting and their impact on climate.

The multitude of processes of various scales occurring simultaneously under strong winds in the air and sea boundary layers presents a true challenge for nonlinear science. We want to understand the physics of these processes, their specific role, their interactions and how they can be probed remotely, how these processes differ from their counterparts under moderate/weak winds. We welcome theoretical, experimental and numerical works on all aspects of processes in turbulent boundary layers above and below the ocean surface. Although we are particularly interested in the processes and phenomena occurring under strong wind conditions, the works concerned with similar processes under weaker winds which might provide an insight for rough seas are also welcomed. We are also very interested in works on remote sensing of these processes.
The areas of interest include the processes at and in the vicinity of the interface (nonlinear dynamics of surface water, wave-turbulence interactions, wave breaking, generation and dynamics of spray and air bubbles, thermodynamics of the processes in the boundary layers, heat and gas exchange), all the processes above and below the aIr/water interface, as long as they are relevant for strong wind conditions (such as, e.g. inertial waves generated by changing winds). Relevant nonlinear biological phenomena are also welcomed.
The main aims of the session is to initiate discussion of the multitude of processes active under strong winds across the narrow specializations as a step towards creating an integrated picture. Theoretical, numerical, experimental and observational works are welcomed.

Geophysical Fluid Dynamics (GFD) is a truly interdisciplinary field, including different topics dealing with rotating stratified fluids. It emerges in the late 50s, when scientists from meteorology, oceanography, astrophysics, geological fluid dynamics, and applied mathematics began to mathematically model complex flows and thereby unify these fields. Since then many new aspects were added and deeper insight into many problems has been achieved. New mathematical and statistical tools were developed, standard techniques were refined, classical problems were varied. In this session we primarily focus on contributions from dynamic meteorology and physical oceanography that model flows by mathematical analysis. However, it is also a forum for experimental GFD and for astrophysical and geological aspects of GFD as well.

Recent years have seen a substantial progress in the understanding of the nonlinear and stochastic processes responsible for important dynamical aspects of the complex Earth system. The Earth system is a complex system with a multitude of spatial and temporal scales which interact nonlinearly with each other. For understanding this complex system new methods from dynamical systems, complex systems theory, complex network theory, statistics and climate and Earth sciences are needed.

In this context the session is open to contributions on all aspects of the nonlinear and stochastic dynamics of the Earth system, including the atmosphere, the ocean and the climate system. Communications based on theoretical and modeling studies, as well as on experimental investigations are welcome. Studies that span the range of model hierarchy from idealized models to complex Earth System Models (ESM), data driven models, use observational data and also theoretical studies are particularly encouraged.

Invited Speaker: Anna von der Heydt (Utrecht University)

Taking inspiration from the Mathematics of Planet Earth 2013 initiative, this session aims at bringing together contributions from the growing interface between the geophysical, the mathematical, and the theoretical physical communities. Specific topics include: PDEs, numerical methods, extreme events, statistical mechanics, pattern formation and emergence, (random and non-autonomous ) dynamical systems, large deviation theory, response theory, tipping points, model reduction techniques, coarse graining, stochastic processes, parametrizations, data assimilation, and thermodynamics. We invite talks and poster both related to specific applications as well as more speculative and theoretical investigations. We particularly encourage early career researchers to present their interdisciplinary work in this session.

Heat extremes are already one of the deadliest meteorological events and they are projected to increase in intensity and frequency due to rising CO2 emissions. The hazard these events pose to society may therefore increase dramatically, and society will need to adapt if the worst impacts are to be avoided. This session therefore welcomes a broad range of new research addressing the challenge of extreme heat. Suitable contributions may: (i) assess the drivers and underlying processes of extreme heat in observations and/or models; (ii) explore the diverse socio-economic impacts of extreme heat events (for example, on aspects relating to human health or economic productivity); (iii) address forecasting of extreme heat at seasonal to sub-seasonal time scales; (iv) focus on societal adaptation to extreme heat, including (but not limited to) the implementation of Heat-Health Early Warning Systems.