The keynote presentation on Flood warnings everywhere - data-driven rainfall-runoff modeling at global scale will be given by Frederik Kratzert from Google Research.

Frederik is a research scientist in the Flood Forecasting team at Google. His academic background is in civil (BSc) and environmental (MSc) engineering, as well as machine learning (PhD). Besides his work and research on the intersection of hydrology and machine learning that mostly focusses on improving reliable and actionable flood forecasts, Frederik also cares deeply about open source software and open data. He is the creator of NeuralHydrology, an open source Python library for training deep learning models in the context of hydrology, and also the creator of Caravan, a global community dataset for large-sample hydrology.

The socio-economic impacts of weather phenomena pose a challenge to carbon-neutral development and highlight society's need for accurate weather forecasts and climate projections. For example, regional weather conditions directly affect renewables-based power systems by modulating power output and demand, and atmospheric extreme events can cause damage or failure of energy infrastructure.

Despite substantial progress in numerical modelling in recent decades, predictability for weather and extreme events is often limited and the assessments of future changes remain uncertain. This underscores the need to improve our understanding of the complex, nonlinear interactions of dynamical and physical processes that influence predictability at different lead times and determine the location, timing, and magnitude of extreme events.

This session will discuss our current understanding of how physical and dynamical processes connect atmospheric motions across temporal and spatial scales and how this relates to intrinsic and practical predictability of various weather phenomena. We particularly welcome contributions advancing our understanding, prediction, and future projections of weather and climate extremes, from both an applied and theoretical viewpoint, and with socio-economic impacts, e.g. on power systems.

Topics of interest include but are not limited to:


(1) Synoptic-scale atmospheric dynamics affecting the timing, positioning, and amplitude of weather events (e.g., the stationarity and amplitude of Rossby waves).
(2) Large-scale atmospheric and oceanic influences (e.g., the stratosphere, the Artic, or tropical oceans) on atmospheric variability and predictability in the midlatitudes.
(3) Intrinsic limits of predictability for various atmospheric phenomena and their link to the multi-scale, non-linear nature of atmospheric dynamics.
(4) Practical limits of predictability and the representation of atmospheric phenomena in numerical weather prediction and climate models including sensitivities to the model physics.
(5) Weather and climate extremes, including compound extreme events, their dynamics, predictability, and representation in weather and climate models.
(6) Statistical and mathematical approaches for the study of extreme events.
(7) Impact and risk assessment analyses of extreme events, in particular with a focus on renewable power systems and Europe.
(8) Extreme event attribution and changes in extreme event occurrences under climate change.

Atmospheric boundary-layer (ABL) processes and their interactions with the underlying surface are crucial for weather, climate, air-quality and renewable-energy forecasts. The multitude of interacting processes act on a variety of temporal and spatial scales and include atmospheric turbulence, atmosphere-soil-vegetation interactions, gravity waves, boundary-layer interactions with dry and moist convection, mesoscale flows, submeso motions, etc.

Although significant advances have been achieved during the last decades, an appropriate comprehension of ABL processes and their interactions under different conditions is still a challenge in meteorology. Improving this knowledge will help to correctly represent ABL processes in weather and climate models, allowing to provide more accurate numerical weather prediction (NWP) forecasts and climate scenarios.

This session welcomes conceptual, observational and modeling research related to the physical processes that appear in the ABL, including those devoted to study the interactions with the free atmosphere. Current contributions evaluating existing models and schemes are also welcome, as well as the presentation of new implementation in numerical modelling.

The following topics are especially encouraged to be submitted to the session:

• Theoretical and experimental studies of the turbulence-closure problem with emphasis on very stable stratification and convection, accounting for interactions between the mean flow, turbulence, internal waves and large-scale self-organized structures.

• Boundary-layer clouds (including fog) and marine, cloud-topped boundary layers: physics and parameterization within NWP and climate models and observational studies.

• Orographic effects: form drag, wave drag and flow blocking, gravity waves.

• Challenges on the surface energy balance and flux aggregation in atmospheric boundary layers over heterogeneous terrain.

• Representation of boundary layers and land-surface interaction in atmospheric models.

• Organization of deep convection across differing atmospheric scales.

• Large-eddy simulation and direct numerical simulation of turbulent flows.

• PBL and surface-layer studies using long-term data (climatology), detailed analysis of case studies and field campaigns presentation.

Atmospheric hazards, for example heavy precipitation or damaging wind gusts, can lead to major material and human losses. Accurately forecasting the meteorological process responsible for the hazard, and the hazard itself, is necessary to protect lives and property. In-depth understanding of these hazards and severe weather phenomena is necessary to accurately represent the relevant processes in models and to forecast them.

With increasing computer power, operational forecast systems have begun to resolve convective scales, yet many hazards are still sub-grid scale phenomena relying on crude parameterizations. However, the promising horizon uncovered by Artificial Intelligence (AI) techniques suggests fruitful synergies between classical computational models and AI to improve severe weather phenomena forecasts.

Furthermore, as our climate changes, certain hazards are likely to become more common and as such an in-depth understanding of how climate change impacts atmospheric hazards is needed.

This session welcomes contributions which increase our understanding of mesoscale and microscale atmospheric processes that might represent a hazard for people, property and the environment. Studies devoted to enhancing our physical and dynamical understanding of severe weather phenomena and their hazards are of particular interest as are contributions incorporating conceptual, observational and modelling research.

Topics of interest include but are not limited to:
1. Deep convection and related hazards: hail, lightning, tornadoes, waterspouts, derechos and downbursts.
2. Mesoscale cyclones (polar lows, medicanes, tropical-like cyclones, mediterranean cyclones) and related hazards: Flash-floods and heavy rain events, strong winds, floods etc.
3. Orographic flows and related hazards: severe gap, barrier, katabatic and foehn winds
4. Cold season hazards: Freezing rain, icing, intense snow falls, cold extremes, fog
5. Warm season hazards: severe droughts, heatwaves

This session provides a platform for contributions on high-resolution precipitation measurements, analyses, and applications in real-time as well as climate studies. Special focus is placed on documenting the benefit of highly spatially and temporally resolved observations of different measurement platforms, e.g. satellites and radar networks. This also comprises the growing field of opportunistic sensing such as retrieving rainfall from microwave links. Papers on monitoring and analyzing extreme precipitation events including extreme value statistics, multi-scale analysis, and event-based data analyses are especially welcome, comprising definitions and applications of indices to characterize extreme precipitation events, e.g. in public communication. Contributions on long-term observations of precipitation and correlations to meteorological and non-meteorological data with respect to climate change studies are cordially invited. In addition, contributions on the development and improvement of gridded reference data sets based on in-situ and remote sensing precipitation measurements are welcome.
High-resolution measurements and analyses of precipitation are crucial, especially in urban areas with high vulnerabilities, in order to describe the hydrological response and improve water risk management. Thus, this session also addresses contributions on the application of high-resolution precipitation data in hydrological impact and design studies.
Acting on this year's focus topic we emphasize the call for contributions on Artificial Intelligence (AI) and Machine Learning (ML) in enhancing environmental monitoring and hydro(meteoro)logical research and applications.

Summarizing, one or more of the following topics shall be addressed:
• Precipitation measurement techniques
• High-resolution precipitation observations from different platforms (e.g., gauges, disdrometers, radars, satellites, microwave links) and their combination
• Precipitation reference data sets (e.g., GPCC, OPERA)
• Drought monitoring and impact
• Statistical analysis of extreme precipitation (events)
• Statistical analysis of changes/trends in precipitation totals (monthly, seasonal, annual)
• Multi-scale analysis, including sub-kilometer scale statistical precipitation description and downscaling methods
• Definition and application of indices to characterize extreme precipitation events
• Climate change studies on extreme precipitation (events)
• Urban hydrology and hydrological impact as well as design studies
• New concepts of adaptation to climate change with respect to extreme precipitation in urban areas
• AI and ML techniques in hydrometeorological and hydrological research and applications

Measurements are essential to provide information on the actual state of the atmosphere for nowcasting purposes, for climate monitoring, for assimilation into numerical weather prediction (NWP) systems, as input to AI algorithms, and to improve our understanding of atmospheric processes and their role in the Earth system. In particular, there is a strong need for complex observations suitable to develop, improve and validate parameterizations used in NWP and climate models and to provide ground-truth against which to compare atmospheric parameters derived from satellite data. With a new generation of high-resolution forecast models (1-3 km) used for the prediction of high-impact weather, dense observational networks focusing on measurements in the lower few kilometers of the atmosphere are required.
This session is intended to give a forum to discuss recent developments and achievements in local to regional measurement concepts and technology. There will be a special emphasis on measurements which seek to improve our understanding of complex atmospheric processes – especially those characterizing interactions in the climate system – through obtaining comprehensive data sets. The focus is on measurements of atmospheric dynamics and thermodynamics, energy and water cycle components, and on the interaction of the atmosphere with the underlying surface.
The session will also include consideration of novel measurement approaches and networks under development for future operational use, e.g., within the frame of the Eumetnet observations program and various COST actions, and the performance of new measurement techniques. Manufacturers of hydro-meteorological instruments and system solutions are thus explicitly invited to present news on sensor development, sensor performance and system integration.
Techniques may cover in-situ and remote sensing measurements from various platforms. Special attention will be given to the creation of a new generation of reliable unmanned instrument networks across Europe that provide calibrated and controlled data on the boundary layer structure in near-real time. This also includes metrological aspects of sensor characterization. Contributions are also welcome that make use of advanced data sets for satellite data validation.
With reference to the special conference focus we specifically invite contributions making use of machine learning techniques for quality control or product generation of atmospheric measurement data.

Cities and urban environments are a key aspect of the United Nations (UN) Agenda for Sustainable Development, and include scientific and socio-economic perspectives. As urbanisation processes continue across the world, its representation and understanding needs to be further improved to fully assess its impact on weather, air quality, water quality, energy consumption/production and climate. These aspects are crucial both for advancing current knowledge and creating effective sustainable solutions. Key challenges in accomplishing this task vary according to the level of complexity and multi-scale dimension of diverse urban environments.

This session welcomes modelling and observational studies that aim to investigate different aspects of urbanization (e.g. urban heat island, air quality, vulnerability to extreme events, urban/peri-urban agriculture) and its feedback on weather and climate systems, with a particular focus on application for sustainable adaptation plans. Novel methods that aim to assess urban representation and/or to bridge the different scales of the diversity of topologies are encouraged. The impact of cities on weather, air quality, climate and/or their extremes (e.g. drought, precipitation, air pollution episodes), as well as on climate change and on population and adaptation will also be discussed in this session.

Topics may include:
• New urban parameterizations, methods to derive urban parameters for numerical models.
• Implementation of climate mitigations, adaptation strategies (e.g. blue-green infrastructures) and self-government policies in cities and urban context.
• Impact of the different urban parameterizations on the atmospheric dynamics at different scales.
• Impact of the urbanization including estate and industrial on weather and/or climate extremes.
• Field measurements of urban climate, e.g. precipitation, CO2 concentrations and flux, boundary layer characteristics.
• Population vulnerability to urban climate and climate change.
• Extreme events' (e.g. drought, rainfall events, heat wave) impacts on urban areas.
• Urban emissions of climate forcers, air pollutants and anthropogenic heat.
• Urban air quality and meteorological interactions.
• Meteorology or air pollution modelling of all scales with focus on urban areas.
• Coupling and downscaling of global, regional and urban scale modelling approaches to quantify climate and atmospheric composition impacts and feedbacks.
• Integrated monitoring, modelling and forecast systems for urban hazards.
• Urban transition to cleaner fuels and their meteorological or AQ impacts.
• Crowd sourced data/novel data sources in cities
• Successes, challenges and limits of AI approaches for urban research
• Assimilation of 4D data and machine learning applied for air quality simulation
• Social science analyses of cities

Organised jointly with:
World Meteorological Organization (WMO) Global Atmospheric Watch Project GAW Urban Research in Meteorology and Environment (GURME)
WMO World Weather Research Programme (WWRP)

Meteorology and hydrology act in tandem across the interface of the earth's surface. Such an interface will become increasingly important as our understanding and predictive capabilities improve. For the good of society, the need to meld together the two disciplines is now more vital than ever. Many national meteorological services worldwide have, formally or informally, evolved into national hydro-meteorological services. The session, introduced in 2019, aims to provide an all-embracing hydro-meteorological forum where experts from both disciplines can combine and exploit their expertise to accelerate the integration of these two fields. We invite contributions that consider physical or machine learning-based approaches, and act across a wide range of spatial scales (from 10s of meters up to global) and a wide range of time scales (from ~1 hour up to seasonal and climate change), including, but not limited to, the following topics:

• Land-atmosphere interactions and hydrological processes, including feedback mechanisms.
• Understanding the meteorological processes driving hydrological extremes.
• Tools, techniques, and expertise in forecasting hydro-meteorological extremes (e.g., river flooding, flash floods, droughts etc.).
• Fully integrated numerical earth system modelling.
• Quantification/propagation of uncertainties in hydro-meteorological model forecasts.
• The role of vegetation in hydro-meteorological extremes, in terms of transpiration, photosynthesis, phenology, etc.
• Energy cycles, complementing the hydrological cycles and related cryospheric processes.
• Hydro-meteorological prediction that includes impacts.
• Environmental variable monitoring by remote sensing and other observations.
• Quantification of (past/future) hydrological trends in observations and climate models (and their role in the 2024 "climate-neutral Europe" conference theme).

This session is open for abstracts on all aspects of solar and terrestrial radiation, clouds and aerosols. We welcome talks and posters on:
- Observations and measurement campaigns including the observation of optical properties of clouds and aerosols
- Radiative transfer in cloud-free and cloudy atmosphere including three-dimensional aspects and complex topography as well as radiative properties of the surface
- Parametrizations of radiation and clouds
- Modelling of radiation and clouds on all time-scales from nowcasting over short- and medium range numerical weather predication to decadal predictions and climate projections
- Verification of NWP and climate model outputs using satellite and ground-based observations
- Validation of satellite products using ground-based observations
- Use of modelled and observed radiation and cloud data in various applications such as renewable energy and agriculture.

This session connects scientists from multiple disciplines to advance our understanding of atmospheric and oceanographic processes in coastal and open-ocean environments, across different time and space scales. We encourage contributions that integrate diverse approaches numerical models (including coupled systems and Digital Twins), observational strategies (in situ, remote sensing), and data-driven methods (machine learning) to tackle complex phenomena such as extreme weather events, air-sea interactions, and coastal-to-global circulation (both in the atmospheric and marine environments). Topics may include, but not limited to, extreme weather events, heatwaves, sea-level changes, coastal circulation, and cross-disciplinary methods for operational forecasting and climate impact assessments. By fostering a collaborative framework, we aim to explore innovative solutions for early warning systems, operational applications, and long-term environmental strategies.

Potential topics include, but are not limited to:
• Extreme weather events (including tropical cyclones, severe wind and wave storms)
• Heatwaves (marine and atmospheric) and their interactions
• Sea-level changes, storm surges, and coastal flooding
• Coastal circulation and sediment dynamics
• Cross-disciplinary methods for operational forecasting and climate impact assessments

While overall the global warming with the causes and global processes connected to well-mixed CO2, and its impacts on global to continental scales are well understood with a high level of confidence, there are knowledge gaps concerning the impact of many other non-CO2 radiative forcers leading to low confidence in the conclusions. This relates mainly to specific anthropogenic and natural precursor emissions of short-lived GHGs and aerosols and their precursors. The anthropogenic origin is connected to large extent with the urban environment. These gaps and uncertainties also exist in their subsequent effects on atmospheric chemistry and climate, through direct emissions dependent on changes in e.g., agriculture production and technologies based on scenarios for future development as well as feedbacks of global warming on emissions, e.g., permafrost thaw. There are a few recent and ongoing EU projects on these topics, like FOCI, OptimESM, CERTAINTY, FORCeS, RESCUE.

Contributions on global to local emissions of such atmospheric constituents and their role in chemistry climate interactions are expected. Their implementation into ESM in global scale as well as in RCM coupled with CTM for regional and local scales can be dealt by the contributions as well, from emission driven simulations in ESM to the local interaction and impacts on climate and vice versa, i.e. climate change affecting local air-quality conditions. Contributions on synergies and benefits in climate change mitigation as well as side impacts on health and environment from the mitigation of air pollution are most welcome as well.

The cryosphere, a critical component of the Earth system, is experiencing significant changes due to climate forcing. While global warming is the overarching driver, the rates, impacts, and processes vary in mountain and Polar regions. Understanding climate-cryosphere interactions across different spatial and temporal scales is essential for estimating the global cryosphere's response to climate change and the consequent impact on other climate system components.

Mountain Regions: In mountainous areas, the cryosphere encompasses seasonal snow cover, glaciers, permafrost, and ice deposits in caves. These elements influence the hydrology of numerous river systems, crucial for water availability, especially in arid high mountain regions. Despite their smaller water volume compared to polar regions, glacier mass loss significantly contributes to rising sea levels. Permafrost degradation poses risks to rock stability and increases the potential for natural hazards. Even the lesser-known permanent ice deposits in caves store vital paleoenvironmental information. Investigating micro-climates over snow and ice surfaces and their links to large-scale weather conditions is crucial for understanding the mass and energy balance of the mountain cryosphere.

Polar Regions: Polar regions exhibit high sensitivity to climate change, exemplified by Arctic amplification. Changes in sea ice and ice sheets in both poles impact global climate through alterations in atmospheric and ocean circulation, sea level, albedo, vegetation, and related feedbacks. The Arctic has witnessed a sharp decline in sea ice extent and volume, with the Greenland Ice Sheet losing mass rapidly. Antarctica, too, shows declining sea ice extent, with unclear signs of recovery. Contrasting trends in the mass balance of the Antarctic ice sheet in its eastern and western parts add complexity. The impacts of these changes in the polar cryosphere on large-scale climate variability through atmospheric and oceanic pathways are uncertain.

Session: This session invites contributions addressing all aspects of cold regions' meteorology and the cryosphere interacting with the past, present, and future climate system from both modeling and observations. We encourage submissions from multiple approaches, i.e. past records, meteorological and geophysical observations, numerical modeling, and downscaling methods aiming to advance the current knowledge of the feedback between the cryosphere and the climate system. Presentations of interdisciplinary studies, as well as detailed process surveys, are highly welcome.

Society will feel the impacts of climate change mainly through extreme weather and climate events, such as heat waves and droughts, heavy rainfall and associated flooding, and extreme winds. Determining from the observational record whether there have been significant changes in the frequency, amplitude and persistence of extreme events poses considerable challenges. Changes in the distributional tails of climate variables may not necessarily be coherent with the changes in their mean values. Also, attributing any such changes to natural or anthropogenic drivers is a challenge.

The aim of this session will be studies that bridge the spatial scales and reach the timescales of extreme events that impact all our lives. Papers are solicited on advancing the understanding of causes of observed changes in mean climate, in its variability and in the frequency and intensity of extreme events. In particular, papers are invited on trends in the regional climate of Europe, not just the mean, but variability and extremes, often for the latter measured through well-chosen indices.

Covariability between remote regions – often named teleconnections – are at the basis of our current knowledge of a large part of Earth’s climate variations and represent an important source of weather and climate predictability. Tropospheric and stratospheric pathways have been suggested to play a role in connecting internally-generated and radiatively-forced anomalies at mid-latitudes, as well as in settling tropical-extratropical and polar-nonpolar interactions. However, the underlying processes behind these linkages are still not properly understood, misled by different metrics and diagnostics, and/or generally poorly simulated by global climate models (GCMs). A continuous assessment of these atmospheric teleconnections is thus necessary, since advances in process understanding could translate into improving climate models and predictions.

This session aims at gathering studies on both empirical and modelling approaches, dealing with a dynamical characterization of coupled processes and teleconnections. It invites contributions using observational datasets; GCM simulations; pre-industrial, present, and future climate conditions; and idealised sensitivity experiments. This session welcomes theoretical approaches and applications oriented to climate forecasting and services.

Synoptic climatology examines all aspects of relationships between large-scale atmospheric circulation on one side, and surface climate and environmental variables on the other. The session addresses all topics of synoptic climatology; nevertheless, we would like to concentrate on the following areas: statistical (empirical) downscaling, circulation and weather classifications, teleconnections and circulation regimes, and climatology of cyclones and other pressure formations, including effects of the circulation features on surface climate conditions. We also encourage submissions on recent climate variability and change studied by tools of synoptic climatology or otherwise related to synoptic-climatological concepts.

We invite contributions on theoretical developments of classification methods as well as on their use in various tasks of atmospheric sciences, such as climate zonation, identification and analysis of circulation and weather types, and synoptic catalogues. Climatological, meteorological, and environmental applications of circulation classifications are particularly welcome.

The session will also include presentations on statistical (empirical) downscaling as a tool for evaluation and reconstruction of historical climate, gap filling in time series, analysis of extremes and non-climatic variables. Also intercomparisons among downscaling methods and their validation belong to this session.

Contributions on teleconnections (modes of low-frequency variability) and circulation regimes are expected to cover particularly their impacts on surface weather, climate, and environment.

The contributions on climatology of cyclones and other pressure formations will include analyses of cyclone tracks, life time and intensity of cyclones, as well as analyses of anticyclones and blockings. We also invite studies on impacts of the pressure formations on the environment and society, their relationships with large scale circulation patterns, as well as analyses of their recent trends and behavior in possible future climates.

The exceptional amplitude and rate of warming recorded at global, hemispherical and regional scales within contemporary instrumental records should be placed in the context of longer-term multi-centennial and millennial climate variability in order to both assess its uniqueness and better understand the mechanisms that contribute to the background of natural climate variability. Systematic meteorological measurements only span over a relatively short time interval. Thus, documentary evidence and natural climate proxies are used for the reconstruction and understanding of longer term past climate variability.

This session welcomes presentations related to various topics related to this frame:
• early instrumental meteorological measurements, their history and use for the long-term series
• documentary evidence and its features (advantages, disadvantages limits)
• natural climate proxies and its features (advantages, disadvantages, limits)
• methodological improvements and analysis of climate reconstruction approaches both from documentary evidence and natural climatic proxies
• results of climate reconstructions over different regions based on various climatic sources
• hydrological and meteorological extremes (e.g. floods, hurricanes, windstorms, tornadoes, hailstorms, frosts) and their human impacts in relation to climate variability beyond the instrumental period.
• climate modelling of the last 2K and comparison of model outputs with reconstructed/observed climatological data
• past impacts of climate variability on natural processes and human society
• past and recent perception of the climate and its variability
• history of meteorology and meteorological and climatological knowledge
• discussion of natural and anthropogenic forcings as well as recent warming at global, regional and local scales in a long-term context.

Observed and future changes, variability, large-scale circulation and climate attribution.

The warming trends detected in the observational record and future projections, accompanied by an increase in hydrological droughts, have designated the Mediterranean basin as one of the most responsive regions to global climate change. As the warming is expected to continue and intensify in the next decades, local communities and decision-makers call for improved climate information that would allow adaptation to changing climate conditions. In recent years, record-breaking temperatures have been registered –with annual-mean anomalies reaching up to 2.5 °C in mountainous regions during 2022 and 2023– together with large rainfall deficits impacting on different socio-economic activities and causing environmental damage over the western Mediterranean basin. However, extreme precipitation events have recently evidenced the exposure and vulnerability of the region.

In this context, a better understanding of the physical mechanisms driving long-term changes in the Mediterranean region, along with a comprehensive assessment of climate simulations, are crucial to increase our confidence in future projections and better estimate the climate risk.

This session aims to present the latest advances in studying Mediterranean climate change, including the use of artificial intelligence algorithms and innovative approaches for attributing climatic trends and events and for process-based model evaluation. Studies of past long-term changes and future projections focused on validating simulated climate variability across time scales and reducing uncertainty are particularly encouraged. Analyses of specific climate hazards and the associated atmospheric circulation (including extremes, teleconnection patterns, and regional-to-local responses) are also welcome.

Climate reanalyses provide a description the of past weather by retrospectively assimilating reprocessed observational datasets ranging from surface stations and satellites with an up-to-date Numerical Weather Prediction (NWP) model. The resulting time series of the atmospheric state is both dynamically consistent and close to observations. A reanalysis typically provides a broad set of atmospheric parameters, containing near surface parameters, (as e.g. temperature and precipitation), as well as parameters at several altitudes (as e.g. wind).

Regional reanalyses are now available for Europe and specific sub-domains, e.g. produced by national meteorological services. Global and regional reanalyses are an important element of the Copernicus Climate Change Services.

The interest in extracting climate information from reanalysis is rising and they are used in a wide range of applications. In recent years, it has become apparent that reanalyses are a popular basis for training in machine learning methods that enable successful AI-based weather forecasts, for example. They therefore play a key role for this year's thematic focus of the conference: "Growing use of AI/ML in atmospheric sciences and meteorological applications"

This session invites papers that:
• Present the status of reanalysis activities in Europe and beyond.
• Explore and demonstrate the capability of global and regional reanalysis data for climate applications, including energy applications.
• Illustrate the role of reanalysis data for machine learning and artificial intelligence.
• Compare different reanalysis (global, regional) with each other and/or observations
• Improve recovery, quality control and uncertainty estimation of related observations
• Analyse the uncertainty budget of the reanalyses and relate to user applications

Extratropical cyclones (ETCs), cut-off lows and mesoscale cyclones play a significant role in driving precipitation extremes and floods across midlatitude regions, with profound implications for hydrology, infrastructure, and climate risk management. While an increase in the intensity of precipitation extremes is generally expected because of thermodynamic effects of climate change, for adaptation purposes it is important to understand the frequency and magnitude of the ongoing changes and the possible amplitude of future worst case events. On one hand, large-scale internal climate variability modulates the occurrence of high-impact cyclones, while on the other hand resolving small-scale convective-scale processes is essential to reproduce precipitation extremes. From a modelling perspective this proves to be a challenge, since large initial-condition ensembles of convective-permitting simulations are currently not feasible.

This session will explore cutting-edge approaches to address this challenge, by gathering contributions showing the value of distilling and combining climate information from diverse datasets and modelling approaches, including: present and future simulations from single model initial-condition large ensemble (SMILEs), regional climate models including convective-permitting simulations (e.g. CORDEX) and regional large ensembles (regional SMILEs), UNSEEN approaches, statistical emulators to combine global and regional models, and the application of AI methods in this research field (e.g. downscaling large ensembles, AI-based precipitation modelling, detection of ETCs in climate models).

We particularly encourage contributions addressing the following topics:

- Novel approaches, e.g. dynamical-statistical emulators or AI-based methods, to combine information from global models with high-resolution regional climate simulations.
- Storylines of worst case extratropical storms due to the combination of climate change and internal variability.
- Projected changes in mid-latitude storm tracks, ETC frequency, intensity, and speed and their influence on extreme precipitation events.
- The added value from regional and convective-permitting simulations in quantifying future trends in extreme precipitation compared to global climate models.
- The role of climate change in intensifying recent European extreme precipitation events.
- Emerging insights from digital twins, e.g. Destination Earth.

The overall aim of the session is to foster discussion and interaction across global and regional modelling research communities to improve regional climate risk assessment.

The isotopic composition of water molecules is a powerful tool for tracing recent and past climate changes. Variations in stable isotopes (¹⁶O, ¹⁷O, ¹⁸O, ¹H, ²H) and radioactive isotopes (³H) reveal changes in temperature, precipitation patterns, evaporation rates, and more. Monitoring the isotopic signatures in precipitation and water sources provides critical insights into local, regional, and global climatic responses to global warming, offering valuable data for understanding and predicting future climate dynamics. Moreover, isotopic analysis of natural archives (ice cores, sediments, tree rings, and fossilized remains) enables the reconstruction of past temperature fluctuations, hydrological cycles, and atmospheric circulation patterns spanning millennia.
This session invites contributions related to atmo-, cryo-, hydro-, and geosphere isotopic investigations of the water cycle to trace recent and past climate change. Participants are invited to submit papers for a special issue of the SCIE journal Acta Geographica Slovenica (https://ojs.zrc-sazu.si/ags).