The socio-economic impact of extreme events, such as the recent summer drought in Europe, highlight society's need for accurate weather forecasts and climate projections. Despite substantial progress in numerical modelling in recent decades, predictability for extreme events is often limited and the assessments of future changes in extremes 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 and prediction of weather and climate extremes, from both an applied and theoretical viewpoint.

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.
(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 above and with the surface below. 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-exchange processes, including soil-vegetation-atmosphere transfers. 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, for example wind gusts, are still sub-grid scale phenomena relying on crude parameterizations. 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. Another focus topic of this session is on improving understanding, observation, and scale-scale modelling of wind gusts irrespective of the atmospheric phenomena responsible for the gusts.

Moreover, in line with this years’ conference theme, we particularly welcome contributions dealing (directly or indirectly) with severe droughts in Europe or connecting drought events and atmospheric hazards.

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
6. Wind gusts: their measurement, modelling, physical understanding, operational forecasting and warning.

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.
According to the special focus of the 2023 Annual Meeting contributions on “Europe and droughts: Hydro-meteorological processes, forecasting and preparedness” are especially encouraged, such as, e.g., contributions on drought monitoring and contributions covering interdisciplinary approaches stretching from hydro-meteorological data to applications in, e.g., risk management and disaster prevention.

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

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 and to improve our understanding of atmospheric processes and their role in the climate 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 (such as PROBE), 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 invited that make use of advanced data sets for satellite data validation.
With reference to the special conference focus (“Europe and droughts”) we particularly invite contributions on measurements of soil moisture and evaporation.

Cities and urban environments are a key aspect of the United Nations (UN) Agenda for Sustainable Development, as well as in recent scientific and socio-economic perspectives. As urbanization processes continue across the world, its representation, impact, and understanding needs to be further studied to fully comprehend its impact on weather, air quality 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.

Urban environments are structurally complex as they span a diversity of typologies, e.g. industrial, residential, and recreational/green areas, which, in turn, have diverse time-varying impacts on the Earth system. Among these are impacts on the air quality, water quality, heat, and energy consumption/production. Furthermore, urban environments often exhibit low resilience to climate change and extreme weather, which further affects the living conditions of urban dwellers.

This session presents and explores aspects of cities and urban environments within the Earth system. We welcome modelling and observational studies that aim to investigate different aspects of urbanization (e.g. urban heat island, air quality, population vulnerability, 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 within numerical models 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 numeric models
• implementation of climate mitigations, adaptation strategies and self-government policies in cities and urban context
• impact of the different urban parameterizations on the atmosphere dynamics and on the different scales
• the impact of the urbanization including estate industrial on weather and/or climate extremes
• field measurements of urban climate, e.g. urban heat island
• impact of different surfaces (green areas, impermeable outer surfaces etc.) on climate and/or its extremes in build-up areas and blue-green infrastructures
• population vulnerability to urban climate and climate change
• extreme events (e.g. drought, rainfall events) impacts on town agglomeration
• urban and peri-urban agriculture
• Urban emissions of climate forcers and air pollutants
• Urban air quality and meteorological interactions
• High resolution and microscale modelling of meteorology and air pollution in urban areas
• Coupling and downscaling of urban, regional and global 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
• Crowd sourced data/novel data sources in cities as well as
• 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 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, etc.); the role of the vegetation in this context, in terms of transpiration, photosynthesis, phenology, etc.; energy cycles, complementing the hydrological cycles and related cryospheric processes; fully integrated numerical earth system modelling; quantification/propagation of uncertainties in hydro-meteorological models; quantification of (past/future) hydrological trends in observations and climate models; hydro-meteorological prediction that includes the associated impacts; environmental variable monitoring by remote sensing and other observations; droughts (in tandem with the 2023 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 is multi-purpose and aims at connecting various experts of the international scientific community that works on atmospheric and oceanographic phenomena as well as air-sea interactions, occurring at different temporal and spatial scales in coastal and open-ocean areas.

This session will welcome contributions using analysis, observations, numerical and machine learning tools, applied to specific case studies, operational applications and related services (such as risk assessment, coastal management, renewable energy spatial planning, coastal erosion and deposition, the resilience of coastal citizens and activity in the context of climate change, etc). The objectives are to foster the connections between atmospheric and oceanographic scientific communities and to promote an integrated and multidisciplinary approach for the analysis observations and the modeling of the Earth system.

In detail, this session will welcome:
I) Numerical studies spanning from uncoupled and coupled numerical models to the Digital-Twins, that analyze dynamics of the ocean, atmosphere, and waves (with particular attention to air-sea interactions), in coastal and open ocean areas.
II) Observational studies using oceanographic (ARGO floats, Gliders and AUV, buoys, Stereo 3D imaging, operational campaigns, and survey, etc) and atmospheric (automatic weather stations, sonic anemometers, disdrometers, etc.) in-situ measurements, ground-based (Coastal High-Frequency Radar (HFR), S, C and X-band weather radar, etc), and space-borne remote sensing techniques (scatterometer, SAR, etc).
III) Application of Machine Learning and Deep Learning Weather and Ocean Prediction techniques both in the ocean and atmospheric environment in support of a wide range of applications, such as: data assimilation systems, ensemble approach and processing, nowcasting numerical schemes, early warning systems, decision support services, physical ocean and atmospheric processes analysis, seasonal and climate projection applications and other experimental study techniques.

We invite contributions including, but not limited to, the following topics:
• Intense cyclones, Medicanes, Air-sea interactions and impacts in coastal areas
• Severe wind storms, Wave storms, Extreme Waves and Storm surges
• Coastal floods and Heavy Precipitation Events (HPEs)
• Sea level oscillations and sea level future projections
• Cold Air Outbreak, Cold and Dry Spells, and feedback with the atmosphere and ocean
• Marine and Atmospheric Heat Waves
• Ocean Heat Content modification and its impact on the atmosphere on short, seasonal and long time scales
• Dense Water Formation processes
• Coastal circulation and Sediment transport

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 mid-latitude atmospheric teleconnections. It invites contributions using observational datasets; coupled and uncoupled (atmosphere-only) GCM simulations; pre-industrial, present, and future climate conditions; idealised sensitivity experiments; or theoretical models.

Keynote talk:

TBD - ""

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.

Prediction and predictability on timescales of several weeks to months is crucial for the advancement of our understanding and modeling of processes on these timescales. These processes include coupling processes in the global climate system, their representation and prediction in model systems, as well as the impacts associated with extreme events that exhibit probabilistic predictability on these timescales. This session invites contributions that span all aspects of prediction and predictability in the lead time range between 2 weeks and seasonal timescales. We encourage submissions on physical processes, including (but not limited to) the Madden Julian Oscillation (MJO), the monsoons, and El Nino Southern Oscillation (ENSO) and their remote effects, coupling between different parts of the globe, the vertical coupling in the atmosphere, as well as coupling between the atmosphere and the underlying surface in terms of land, ocean and the cryosphere. We further invite contributions on ensemble prediction and analysis methods as well as impact-based methods for socio-economic impacts related to processes and predictability on sub-seasonal to seasonal timescales.

Improved reanalyses of past weather can be obtained by retrospectively assimilating reprocessed observational datasets ranging from surface stations and satellites with a up-to-date Numerical Weather Prediction (NWP) model. The resulting time series of the atmospheric state is both dynamically consistent and close to observations. The interest in extracting climate information from reanalysis is rising and creating a request for reanalysis uncertainty estimation at various temporal-spatial scales.
These research questions have been addressed in EU-funded research projects (e.g.ERA-CLIM, EURO4M and UERRA). Regional reanalyses are now available for Europe and specific sub-domains, e.g. produced by national meteorological services. Global and regional reanalyses are also an important element of the Copernicus Climate Change Services.

This session invites papers that:
• Explore and demonstrate the capability of global and regional reanalysis data for climate applications
• 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