Smart monitoring and observation systems for hazards, including satellites, seismometers, global networks, uncrewed vehicles (e.g., UAV), and other linked devices, have become increasingly abundant. With these data, we observe our Earth’s restless nature and work towards improving our understanding of hazard processes such as landslides, debris flows, earthquakes, floods, storms, volcanic eruptions, and tsunamis. The large amount of data we have now accumulated with diverse measurements presents an opportunity for earth scientists to employ statistically driven approaches that speed up data processing, improve model forecasts, and give insights into the underlying physical processes. Such big-data approaches are supported by the wider scientific, computational, and statistical research communities who are constantly developing data science and machine learning techniques and software. Hence, data science and machine learning methods are rapidly impacting the fields of geohazards. In this session, we will see research into hazards spanning a broad range of time and spatial scales.

Extreme events and natural hazards are frequent occurrences on our unstable planet. They are predicted to become more common, severe and costly in the future and this session explores their role in human prehistory and history. In order to understand the potential of contemporary and future extreme events to impact human societies, it is critical to understand the mechanisms of how they may have occurred in the past, and elucidate their effects. This session invites contributions from across relevant disciplines. Global in scope and not limited to specific types of extreme events or natural hazards, we hope to compare and contrast differing methods and datasets that address the character and role of extreme events in the human past. Ultimately, we also seek to discuss how the evidence base of Pleistocene and Holocene calamities can be brought into play in the discussion about sustainability and disaster risk reduction in the Anthropocene, as well as to explore how extreme events may have shaped our past.

This session is a merge session and jointly lead by the group of NH1.1 and NH1.2.
NH1.1: Innovative Techniques for Flood Forecasting, Assessment and Flood Risk Management
This session invites presentations on research based on high-resolution aerial, satellite and ML techniques for flood monitoring and modeling, including mapping of inundation extent, flow depths, velocity fields, flood-induced morphodynamics, and 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 a 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, ML and modelling techniques, as well as assessment of uncertainties in real-time aerial surveying are welcome in this session. We also encourage contributions in integrative solutions at local, regional or global perspectives. Invited Speaker: Prof.Paul Bates (https://research-information.bris.ac.uk/en/persons/paul-d-bates)
NH1.2: Advances in modeling, failure assessment and monitoring of levees and other flood defences
The present session aims to provide a platform for the interdisciplinary exchange of knowledge among flood risk and other flood hazard related scientific communities interested in the modeling, assessment and monitoring of soil made flood defences, to share their experiences and advances in the field. Hence the session aims to present contributions regarding: 1) Numerical and experimental advances on failure mechanism understanding (e.g. Overtopping, piping erosion, Slope stability, etc) 2) Probabilistic assessment of flood defence design and reliability assessment. 3) Monitoring techniques of flood defences based on remote and direct instrumentation. 4) Alternative flood defence studies for evaluation of effect and performance of controlled failure, retention basins and fast infiltration surfaces on inundation models. 5) Artificial intelligence and data driven techniques for modeling, assessment and monitoring of soil flood defences.

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.

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

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/)

Lightning is the energetic manifestation of electrical breakdown in the atmosphere, occurring as a result of charge separation processes operating on micro and macro-scales, leading to strong electric fields within thunderstorms. Lightning is associated with tropical storms and 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 with 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 with emphasis on:

Atmospheric electricity in fair weather and the global electrical circuit
Effects of dust and volcanic ash on atmospheric electricity
Thunderstorm dynamics and microphysics
Middle atmospheric Transient Luminous Events
Energetic radiation from thunderstorms and lightning
Experimental investigations of lightning discharge physics processes
Remote sensing of lightning and related phenomena by ASIM and GLM
Thunderstorms, flash floods, tropical storms and severe weather
Modeling of thunderstorms and lightning
Now-casting and forecasting of thunderstorms using machine learning and AI
Regional and global lightning detection networks
Lightning Safety and its Societal Effects

With global climate change affecting the frequency and severity of extreme meteorological and hydrological events, it is particularly necessary to develop models and methodologies for a better understanding and forecasting of present day weather induced hazards. Future changes in the event characteristics as well as changes in vulnerability and exposure are among the further factors for determining risks for infrastructure and society, and for the development of suitable adaptation measures. 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 or sequences 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 applications like insurance issues.

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 data acquisition, development and hydrological application of mathematical modelling, information technology, systems science and computational intelligence tools. We also have to face the challenges of the so-called Big Data: large data sets, both in size and complexity. Methods and technologies for data handling, visualization and knowledge acquisition are 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. We aim to address the following classes of methods and technologies:

* Predictive and analytical models based on the methods of statistics, computational intelligence, machine learning : neural networks (including deep learning), fuzzy systems, genetic programming, cellular automata, chaos theory, etc.
* Innovative sensing techniques: satellites, gauges and citizens (crowdsourcing)
* 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 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.

This session provides a platform for transdisciplinary science that addresses the continuum of the river and its catchment to the coastal sea. We invite studies across geographical borders; from the source to the sea including groundwater, and across the freshwater-marine water transition, including estuaries, deltas and marshlands. The session particularly welcomes studies that link environmental and social science, addressing the impacts of climate change and extreme events and impact of human activities on water and sediment quality and quantity, hydromorphology, biodiversity, ecosystem functioning and services of River-Sea continua. Such a systems approach is required to develop solutions for sustainable management of River-Sea social-ecological systems.

We need to fully understand how River-Sea Systems function. How are River-Sea continua changing due to human pressures? What is the impact of processes in the catchment on coastal and marine systems function, and vice versa? How can we discern between human-induced changes or those driven by natural processes from climate-induced variability and extreme events? What will the tipping points of socio-ecologic system states be and what will they look like? How can we better characterise river-sea systems from the latest generation Earth observation to citizen science based observatories. How can we predict short and long term changes in River-Sea-Systems to manage them sustainably? What is the limit to which it is possible to predict the natural and human-influenced evolution of River-Sea-Systems? The increasing demand to jointly enable intensive human use and environmental protection in River-Sea Systems requires holistic and integrative research approaches with the ultimate goal of enhanced system understanding as the knowledge base for sustainable management solutions.

Water is our planet’s most vital resource, and the primary agent in some of the biggest hazards facing society and nature. The twin pressures of population growth and a rapidly changing global climate act as multipliers of water’s value and of water-related hazards.

River streamflow is one of the most crucial hydrological variables for ecology, for people and industry, for flood risk management and for understanding long term changes to the hydrological regime. However, despite significant efforts, long-term, spatially dense monitoring networks remain scarce, and even the best monitoring networks can fail to perform when faced with extreme conditions, and lack the precision and spatial coverage to fully represent crucial aspects of the hydrological cycle.

Happily, a number of new technologies and techniques are emerging which show great potential to meet these challenges. In this context, this session focuses on:
1) Innovative methodologies for measuring/modelling/estimating river stream flows;
2) Real-time acquisition of hydrological variables;
3) Remote sensing for hydrological & morphological monitoring;
4) Measuring extreme conditions associated with a changing climate;
5) Measurement of sudden-onset extreme flows associated with catastrophic events;
6) Strategies to quantify and describe hydro-morphological evolution of rivers;
7) New methods to cope with data-scarce environments;
8) Inter-comparison of innovative & classical models and approaches;
9) Evolution and refinement of existing methods;
10) Guidelines and standards for hydro-morphological streamflow monitoring;
11) Quantification of uncertainties;
12) Development of expert networks to advance methods.

Contributions are welcome with an emphasis on innovation, efficiency, operator safety, and meeting the growing challenges associated with the changing climate, and with natural and anthropogenically driven disasters such as dam failures and flash floods.

Additionally, presentations will be welcomed which explore options for greater collaboration in advancing riverflow methods and which link innovative research to operational monitoring.

This session is sponsored by the COST Action CA16219, Harmonisation of UAS techniques for agricultural and natural ecosystems monitoring (HARMONIOUS).

The global cryosphere with all its components is strongly impacted by climate change and has been undergoing significant changes over the past decades. Glaciers are shrinking and thinning. Snow cover and duration is reduced, and permafrost, in both Arctic and mountain environments, is thawing. Changes in sea ice cover and characteristics have attracted widespread attention, and changes in ice sheets are monitored with care and concern. Risks associated with one or several of these cryosphere components have been present throughout history. However, with ongoing climate change, we expect changes in the magnitude and frequency of hazards with profound implications for risks, especially when these interact with other aspects relating to context vulnerability, exposure, and other processes of biophysical and/or socioeconomic drivers of change. New or growing glacier lakes pose a threat to downstream communities through the potential for sudden drainage. Thawing permafrost can destabilize mountain slopes, and eventually result in large landslide or destructive rock and ice avalanches. An accelerated rate of permafrost degradation in low-land areas poses risk to existing and planned infrastructure and raises concerns about large-scale emission of greenhouse gases currently trapped in Arctic permafrost. Decreased summertime sea ice extent may produce both risks and opportunities in terms of large-scale climate feedbacks and alterations, coastal vulnerability, and new access to transport routes and natural resources. Furthermore, rapid acceleration of outlet glacier ice discharge and collapse of ice sheets is of major concern for sea level change. This session invites contributions across all cryosphere components that address risks associated with observed or projected physical processes. Contributions considering more than one cryosphere component (e.g. glaciers and permafrost) are particularly encouraged, as well as contributions on cascading processes and interconnected risks. Contributions can consider hazards and risks related to changes in the past, present or future. Furthermore, Contributions may consider one or several components of risks (i.e. natural hazards, exposure, vulnerability) as long as conceptual clarity is ensured. Furthermore, cases that explore diverse experiences with inter- and transdisciplinary research, that sought to address these risks with communities through adaptation and resilience building, are also be considered.

This session is devoted to the dynamics of dense and powder snow avalanches and their accompanying transitional regimes. One focus is their interaction with, and impact on, vulnerable elements, such as buildings, protection dams, forests, and roads. We welcome novel experimental and computational contributions including, but not limited to the topics of avalanche dynamics and related processes, physical vulnerability of structures impacted by snow avalanches, avalanche hazard zoning and avalanche mitigation strategies. These include field, laboratory and numerical studies that rely on new methods and techniques (radars, drone, satellite, etc.) as well as practical case studies.

Furthermore, we solicit novel contributions from the area of granular flows, viscoplastic flows, density currents, turbulent flows, as well as contributions from other gravitational mass flows communities, which can improve our understanding and modeling of snow avalanche propagation and their interaction with natural or man-made structures.

While the main focus of this session is on snow avalanche dynamics from basic knowledge to mitigation strategies, it is closely linked to CR session entitled "Snow avalanche formation: from snow mechanics to avalanche detection" which addresses avalanche formation, detection and forecasting.

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.

Over the last decades, a significant body of empirical and theoretical work has revealed the departure of statistical properties of hydrometeorological processes from the classical statistical prototype, as well as the scaling behaviour of their variables in general, and extremes in particular, in either state, space and/or time. In the meantime, extremes and more generally the statistics of hydrometeorologic processes are the key input for hydrological applications. As a classic example the estimation of design rainfall should be mentioned. Beside the estimation of the absolute rainfall amount related to a certain return period, the intra-event rainfall distribution, its spatial extension and the rainfall intensities at neighbouring stations can be required, depending on the intended application and thus the analysed scale. But design rainfall is only one among numerous hydrologic applications, which shape the framework for this session.

The estimation of the hydrometeorological extremes and probability distribution, the identification and involvement of supporting information and the hydrologic application over wide range of scales are open challenges, especially under non-stationary conditions. On the other side, hydrometeorologists had never access to so much computer power and data to face these open challenges.

This session welcomes, but is not limited to submissions on:
- Coupling stochastic approaches with deterministic hydrometeorological predictions, in order to better represent predictive uncertainty
- Development of robust statistics under non-stationary conditions for dimensioning purposes
- Development of parsimonious representations of probability distributions of hydrometeorological extremes over a wide range of scales in risk analysis applications and hazard prediction
- Improvements for reliable estimation of extremes with high return periods under consideration of upper or lower limits due to physical constraints
- Linking underlying physics and stochastics of hydrometeorologic extremes
- Exploration of supporting data sets for additional stochastic information (e.g. unintended use of other measurements, citizen scientist data, soft data, …)

An overall aim of the session is to bridge the gap between the theoretical stochastic analysis of hydrometeorological processes and its practical hydrological application.

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.

Extreme hydro-meteorological events drive many hydrologic and geomorphic hazards, such as floods, landslides and debris flows, which pose a significant threat to modern societies on a global scale. The continuous increase of population and urban settlements in hazard-prone areas in combination with evidence of changes in extreme weather events lead to a continuous increase in the risk associated with weather-induced hazards. To improve resilience and to design more effective mitigation strategies, we need to better understand the aspects of vulnerability, risk, and triggers that are associated with these hazards.

This session aims at gathering contributions dealing with various hydro-meteorological hazards that address the aspects of vulnerability analysis, risk estimation, impact assessment, mitigation policies and communication strategies. Specifically, we aim to collect contributions from the academia, the industry (e.g. insurance) and government agencies (e.g. civil protection) that will help identify the latest developments and ways forward for increasing the resilience of communities at local, regional and national scales, and proposals for improving the interaction between different entities and sciences.

Contributions focusing on, but not limited to, novel developments and findings on the following topics are particularly encouraged:
- Physical and social vulnerability analysis and impact assessment of hydro-meteorological hazards
- Advances in the estimation of socioeconomic risk from hydro-meteorological hazards
- Characteristics of weather and precipitation patterns leading to high-impact events
- Relationship between weather and precipitation patterns and socio-economic impacts
- Hazard mitigation procedures
- Strategies for increasing public awareness, preparedness, and self-protective response
- Impact-based forecast and warning systems
- Insurance and reinsurance applications

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.

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 and/or rainfall-induced geomorphic hazards monitoring (including in-situ sensors and remote sensing data, such as 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 monitoring or forecasting chains,
- Use of new criteria such as specific “hydrological signatures” (high water marks, impacts and damages, ..) or other proxy data 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.

Hydrological forecasting can benefit from a better understanding of urban floods and of the thresholds values of the hydrological variables that are crucial for making decisions. This session addresses these two aspects.
Urban flooding is becoming a major issue in many megacities around the world due to a lack of adequate storm water management, hydrologic design, and failure of aging hydrologic infrastructure. To model such extreme flood events, it is of utmost importance to develop state-of-the-art disaster mitigation and damage reduction measures, as well as one and two-dimensional hydrologic and coupled hydrodynamic modelling approaches. Innovative methods are needed to address the modelling and management of urban floods and their spatial and temporal complexity. The session discusses urban floods analysis and measures to mitigate the effects of these events, emerging (e.g., Internet-of-Things (IoT)-based) flood monitoring systems, street-level flood forecasting, dissemination of flood warnings and measures to evacuate people, case studies that provide a better understanding of urban flood management, and innovative methods of floodwater conservation, including strategies and practices to control surface runoff at its sources in a sustainable way.
In hydrological forecasting, where the stochastic nature of the processes makes impossible a deterministic forecast of both the magnitude of the processes and their effects, threshold values can be of great importance and usefulness. Thresholds can be simple (e.g., the threshold of rainfall intensity that might separate stratiform from convective rainfall) or complex and multi-variate (e.g., the threshold for damaging snow-melt flooding, or the threshold for intense hillslope erosion in an agricultural field). They can be useful for real-time forecasts based on simple thresholds on rainfall data (e.g., activation of mass movements such as landslides, debris flow, rill and inter-rill erosion, etc.), for the adoption of satellite data in the management of ground actions (e.g., values of the satellite indexes to be used in irrigation management), for distinguishing among water flow regimes, among other applications.

Drought and water scarcity are important issues in many regions of the Earth. While an increase in the severity and frequency of droughts can lead to water scarcity situations, particularly in regions that are already water-stressed, overexploitation of available water resources can exacerbate the consequences of droughts. In the worst case, this can lead to long-term environmental and socio-economic impacts. It is, therefore, necessary to improve both monitoring and sub-seasonal to seasonal forecasting for droughts and water availability and to develop innovative indicators and methodologies that translate the information provided into effective drought early warning and risk management. This session addresses statistical, remote sensing and physically-based techniques, aimed at monitoring, modelling and forecasting hydro-meteorological variables relevant to drought and/or water scarcity. These include, but are not limited to, precipitation, snow cover, soil moisture, streamflow, groundwater levels, and extreme temperatures. The development and implementation of drought indicators meaningful to decision-making processes, and ways of presenting and explaining them to water managers, policymakers and other stakeholders, are further issues that are addressed. The session aims to bring together scientists, practitioners and stakeholders in the fields of hydrology and meteorology, as well as in the field of water resources and/or risk management; interested in monitoring, modelling and forecasting drought and water scarcity, and in analyzing their interrelationships, hydrological impacts, and the feedbacks with society. Particularly welcome are applications and real-world case studies in regions subject to significant water stress, where the importance of drought warning, supported through state-of-the-art monitoring and forecasting of water resources availability is likely to become more important in the future. Contributors to the session are invited to submit papers to the Special Issue (SI) entitled "Recent advances in drought and water scarcity monitoring, modelling, and forecasting", to be published in the open-access journal Natural Hazard and Earth System Sciences (https://www.natural-hazards-and-earth-system-sciences.net/special_issues/schedule.html). Submission is open until 31 December 2020, for manuscripts that are not under consideration for publication elsewhere.

Transport of sediments in geophysical flows occurs in mountainous, fluvial, estuarine, coastal, aeolian and other natural or man-made environments on Earth and has been shown to play important formative roles in planets and satellites such as Mars, Titan, and Venus. Understanding the motion of sediments is still one of the most fundamental problems in hydrological and geophysical sciences. Such processes can vary across a wide range of scales - from the particle to the landscape - which can directly impact both the form (geomorphology) and, on Earth, the function (ecology and biology) of natural systems and the built infrastructure surrounding them. In particular, feedback between flow and sediment transport as well as interparticle interactions including size sorting are a key processes in surface dynamics, finding a range of important applications, from hydraulic engineering and natural hazard mitigation to landscape evolution and river ecology.

Specific topics of interest include (but are not restricted to):

A) particle-scale interactions and transport processes:
-mechanics of entrainment and disentrainment (for fluvial and aeolian flows)
-momentum (turbulent impulses) and energy transfer between turbulent flows and particles
-upscaling and averaging techniques for stochastic transport processes
-interaction among grain sizes in poorly sorted mixtures, including particle segregation

B) reach-scale sediment transport and geomorphic processes
-bedform generation, evolution and disintegration dynamics (e.g. for dunes and other formations)
-discrete element modelling of transport processes and upscaling into continuum frameworks
-derivation and solution of equations for multiphase flows (including fluvial and aeolian flows)
-shallow water hydro-sediment-morphodynamic processes

C) large-scale, highly unsteady and complex water-sediment flows:
-flash floods, debris flows and landslides due to extreme rainfall
-natural and build dam failures and compound disasters (due to landslides, debris flow intrusion and downstream flooding)
-reservoir operation schemes and corresponding fluvial processes
-design of hydraulic structures such as fish passages, dam spillways, also considering the impact of sediment
-dredging, maintenance and regulation for large rivers and navigational waterways

Snow avalanches range among the most prominent natural hazards which threaten mountain communities worldwide. Snow avalanche formation is a complex critical phenomenon which starts with failure processes at the scale of snow crystals and ends with the release of a large volume of snow at a scale of up to several hundred meters. The practical application of avalanche formation is avalanche forecasting, requiring a thorough understanding of the physical and mechanical properties of snow as well as the influence of meteorological boundary conditions (e.g. precipitation, wind and radiation).

This session aims to improve our understanding of avalanche formation processes and to foster the application to avalanche forecasting. We therefore welcome contributions from novel field, laboratory and numerical studies on topics including, but not limited to, the mechanical properties of snow, snow cover simulations, snow instability assessment, meteorological driving factors including drifting and blowing snow, spatial variability, avalanche release mechanics, remote avalanche detection and avalanche forecasting. While the main focus of this session is on avalanche formation, detection and forecasting, it is closely linked to session ‘CR5.2 Snow avalanche dynamics: from basic physical knowledge to mitigation strategies’, which addresses avalanche dynamics, risk assessment and mitigation strategies.

Worldwide over 500 million people live in low-lying coastal deltaic areas, existential to global food security, economic activities and biodiversity. Despite climate change severity at global scale, in many densely populated deltas its effect is currently evidently dwarfed by anthropogenic pressures in the river basin such as river flow modifications, damming and the overexploitation of the natural resources groundwater or sand, as well as profound land use changes and process such as urbanisation. As a result, many major deltas rapidly sink and shrink because of accelerated land subsidence and erosion rates. This increases relative sea-level rise and vulnerability to floods and storms, increases salinization of surface and groundwater and reduces freshwater availability, leading to significant losses in biodiversity, habitat degradation, reduced agricultural and economic productivity. A fundamental change in management approach is required to address these trends and challenges to sustain deltas environments, economies and populations through the 21st Century.

The processes resulting in sinking, shrinking and saltier deltas are interconnected and developing sustainable and inclusive management requires a multidisciplinary system approach. For this, we need to understand the full range of interrelated disciplines, including, amongst others, geology, river and estuarine dynamics, sediment dynamics, hydrology, hydrogeology, geomechanics, bio-morphodynamics as well as the human dimension of delta demography, economy and land use. This session aims to bring together contributions from the full range of scientific disciplines involved in understanding and managing the combined integrated environmental threats that our world’s deltas face. These includes recent advancements in measuring, modeling and projecting environmental dynamics, especially focused on distinguishing (quantifying) anthropogenic and climate change impacts on observed natural dynamics. In particular, inter- and multidisciplinary contributions on the interactions between different environmental processes and efforts towards developing integrated management and development strategies for our sinking, shrinking and saltier deltas are warmly welcomed.

Atmosphere and Cryosphere are closely linked and need to be investigated as an interdisciplinary subject. Most of the cryospheric areas have undergone severe changes in last decades while such areas have been more fragile and less adaptable to global climate changes. This AS-CR session invites model- and observational-based investigations on any aspects of linkages between atmospheric processes and snow and ice on local, regional and global scales. Emphasis is given on the Arctic, high latitudes and altitudes, mountains, sea ice, Antarctic regions. In particular, we encourage studies that address aerosols (such as Black Carbon, Organic Carbon, dust, volcanic ash, diatoms, bioaerosols, bacteria, etc.) and changes in the cryosphere, e.g., effects on snow/ice melt and albedo. The session also focuses on dust transport, aeolian deposition, and volcanic dust, including health, environmental or climate impacts at high latitudes, high altitudes and cold Polar Regions. We include contributions on biological and ecological sciences including dust-organisms interactions, cryoconites, bio-albedo, eco-physiological, biogeochemical and genomic studies. Related topics are light absorbing impurities, cold deserts, dust storms, long-range transport, glaciers darkening, polar ecology, and more. The scientific understanding of the AS-CR interaction needs to be addressed better and linked to the global climate predictions scenarios.

Nature-based Solutions (NBS) are reframing discussion and policy responses worldwide to environmental challenges. Thus, NBS is of growing implementation, supported namely by the EU political agenda (e.g., green deal), as a way to attain the United Nations (UN) Sustainable Development Goals (SDG), and to reinforce the New Urban Agenda. The NBS concept recognise the importance of nature and outline requirements for a systemic and holistic approach to environmental change, based on an understanding of the structure and functioning of ecosystems, and the social and institutional context within which they are situated. Furthermore, there is a growing recognition that human activities exert pressure on natural resources affecting the ecosystem dynamics and therefore the nexus (synergies and trade-offs) between their different functions and services. However, quantification of existing NBS’ effectiveness, their operationalisation and replication in different environmental settings has not been presented in such a way that allows them to be both widely accepted and incorporated in policy development and in practical implementation to achieve the UN SDGs.
This session aims to discuss and advance knowledge of innovative NBS approaches to face environmental challenges, such as water supply and management, agricultural production and healthy ecosystems, and simultaneously provide better understanding of associated social-ecological interactions, contributing to enhance the scientific basis for sustainable development and resilience.
This session seeks to:
- Better understanding of advantages and disadvantages of NBS to address global environmental and societal challenges;
- Studies on adaptation and mitigation options for the effect of climate change on water provisioning and livelihoods;
- New methods and tools to investigate the role of NBS in the context of environmental change; in particular, the effectiveness of NBS for hydro-meteorological risk reduction at landscape/watershed scale;
- New insights, methodologies, tools and best practices enabling successful implementation and upscaling of NBS in multiple contexts;
- Identifying opportunities for and barriers to NBS within current regulatory frameworks and management practices;
- Presenting overviews and case studies of NBS projects that also involve the private sector and market-based mechanisms;
- NBS towards achieving the Sustainable Development Goals (SDGs).

As highlighted by the UN development goals, climate change is a reality to which we need to adapt. Our ability to effectively address the adaptation issue must come from a communal effort to link our knowledge in different fields and transform it into useful information for stakeholders and policymakers.

Up to now, physical climate modelling and natural hazard impact and risk assessment have been two separate disciplines that have suffered difficulties in communicating and interacting due to different languages and backgrounds. Until recently, climate modellers did not have the capability to generate long-term projections at a spatial and temporal resolution useful for impact studies such as flood risk assessment, soil erosion or urban modelling. With the advent of kilometre-scale atmospheric models, called convection-permitting models CPMs, we are now in a position to bridge the gap between the two communities, sharing knowledge and understanding. Compared to traditional climate models, CPMs improve substantially the representation of sub-daily precipitation characteristics and have a spatial resolution closer to what many impacts modellers, for example hydrologists, need. Several CPM datasets are already available over different parts of the world and more internationally coordinated projects on CPMs, such as the CORDEX Flagship Pilot Study (CORDEX-FPS) and the European Climate Prediction System (EUCP), are already in place. Now is the time to exploit these high-resolution physically-consistent datasets as input for impact studies and adaptation strategies; to foster interdisciplinary collaboration to build a common language and understand limitations and needs of the different fields; to learn together how to provide policymakers with information and practical cases that can be used to design effective measures at the regional level to adapt to climate change as well as to inform mitigation decisions.

This interdisciplinary session invites contributions that address the linkages between high-resolution modellers and users with examples of good practice, storylines and communication to both stakeholders and policymakers.

Predictions of climate from seasonal to decadal time scales and their applications will be discussed in this session. With a time horizon from a few months up to thirty years, such predictions are of major importance to society, and improving them presents an interesting scientific challenge. This session aims to embrace advances in our understanding of the origins of seasonal to decadal predictability, as well as in improving the respective forecast skill and making the most of this information by building and testing new applications and climate services.

The session will cover dynamical as well as statistical predictions (including machine learning methods), and their combination. It will investigate predictions of various climate phenomena, including extremes, from global to regional scales, and from seasonal to multidecadal time scales ("seamless predictions"). Physical processes relevant to long-term predictability sources (e.g. ocean, cryosphere, or land) as well as predicting large-scale atmospheric circulation anomalies associated to teleconnections will be discussed, as will observational and emergent constraints on climate variability and predictability on the seasonal-to-(multi)decadal time scale. Also, the time-dependence of the predictive skill, or windows of opportunity (hindcast period), will be investigated. Analysis of predictions in a multi-model framework, and ensemble forecast initialization and generation, including innovative ensemble approaches to minimize initialization shocks, will be another focus of the session. The session will pay particular attention to innovative methods of quality assessment and verification of climate predictions, including extreme-weather frequencies, post-processing of climate hindcasts and forecasts, and quantification and interpretation of model uncertainty. We particularly invite contributions presenting the use of seasonal-to-decadal predictions for risk assessment, adaptation and further applications.

One of the big challenges in Earth system science consists in providing reliable climate predictions on sub-seasonal, seasonal, decadal and longer timescales. The resulting data have the potential to be translated into climate information leading to a better assessment of multi-scale global and regional climate-related risks.
The latest developments and progress in climate forecasting on subseasonal-to-decadal and longer timescales will be discussed and evaluated. This will include presentations and discussions of predictions for a time horizon of up to ten years from dynamical ensemble and statistical/empirical forecast systems, as well as the aspects required for their application: forecast quality assessment, multi-model combination, bias adjustment, downscaling, etc.
Following the new WCPR strategic plan for 2019-2029, prediction enhancements are solicited from contributions embracing climate forecasting from an Earth system science perspective. This includes the study of coupled processes, impacts of coupling and feedbacks, and analysis/verification of the coupled atmosphere-ocean, atmosphere-land, atmosphere-hydrology, atmosphere-chemistry & aerosols, atmosphere-ice, ocean-hydrology, ocean-ice, ocean-chemistry and climate-biosphere (including human component). Contributions are also sought on initialization methods that optimally use observations from different Earth system components, on assessing and mitigating the impacts of model errors on skill, and on ensemble methods.
We also encourage contributions on the use of climate predictions for climate impact assessment, demonstrations of end-user value for climate risk applications and climate-change adaptation and the development of early warning systems.

A special focus will be put on the use of operational climate predictions (C3S, NMME, S2S), results from the CMIP5-CMIP6 decadal prediction experiments, and climate-prediction research and application projects (e.g. EUCP, APPLICATE, PREFACE, MIKLIP, MEDSCOPE, SECLI-FIRM, S2S4E, CONFESS).
An increasingly important aspect for climate forecast's applications is the use of most appropriate downscaling methods, based on dynamical or statistical approaches or their combination, that are needed to generate time series and fields with an appropriate spatial or temporal resolution. This is extensively considered in the session, which therefore brings together scientists from all geoscientific disciplines working on the prediction and application problems.

Weather and Climate Services (WCS) involve the production, translation, delivery, and use of science-based information for decision-making. The production of WCS makes use of long-term climate projections, climate and weather predictions from daily to decadal timescales, historical hydrometeorological data, and sectoral models to predict risks of climate impacts to society. These services are developed and delivered in support of (i) climate-sensitive sectors such as agriculture, management of water resource, health, energy and disaster risk reduction, and (ii) developing countries where the vulnerability to climate change and extreme weather events is high. This session, interdisciplinary in nature, aims at showcasing tools, products and methodologies that could be standardized for an operational and innovative system of WCS delivery in developing countries. The session invites contributions that include a) improvements of models and data analysis for WCS; b) engagement with end-users of WCS; c) assessment of the value of WCS’s outcomes and the corresponding impacts on societies and the environment; d) strategies for broad communication of WCS information to multiple audiences; and e) WCS partnerships between multiple stakeholders such as end-users, NGOs, government ministries, policymakers, and the private sector. The session particularly encourages lessons learned and results from different case studies coming from the global South.

Forecasting the weather, in particular severe and extreme weather has always been the most important subject in meteorology. This session will focus on recent research and developments on forecasting techniques, in particular those designed for operations and impact oriented. Contributions related to nowcasting, meso-scale and convection permitting modelling, ensemble prediction techniques, and statistical post-processing are very welcome.
Topics may include:
 Nowcasting methods and systems, use of observations and weather analysis
 Mesoscale and convection permitting modelling
 Ensemble prediction techniques
 Ensemble-based products for severe/extreme weather forecasting
 Seamless deterministic and probabilistic forecast prediction
 Post-processing techniques, statistical methods in prediction
 Use of machine learning, data mining and other advanced analytical techniques
 Impact oriented weather forecasting
 Presentation of results from relevant international research projects of EU, WMO, and EUMETNET etc.

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?

Volcanic hazards and risk lie at the heart of global geoscience, with about 800 million people threatened by eruptions and other related phenomena. Volcanoes strongly affect humans and the environment through submarine explosions, tephra fallout, pyroclastic flows, earthquakes, tsunamis, and ocean acidification. Evaluation of the impact of volcanic activity on a given region mostly relies on the reconstruction of the eruptive history of volcanoes through the identification, correlation and dating of tephra layers preserved in terrestrial and marine depositional records. In addition, more recent interdisciplinary studies are being used to deepen our understanding of the formation and destruction of volcanoes and the accompanying mass transport processes, as they might significantly contribute to the volcanic hazard assessment. This session will focus on different approaches for reconstructing the history, processes, and evolution of volcanic regions. We invite contributions from all related scientific fields to derive a more comprehensive perspective on the past and present impact of volcanic eruptions, and their potential impacts on the environment and surrounding populations.

The session deals with the documentation and modelling of the tectonic, deformation and geodetic features of any type of volcanic area, on Earth and in the Solar System. The focus is on advancing our understanding on any type of deformation of active and non-active volcanoes, on the associated behaviours, and the implications for hazards. We welcome contributions based on results from fieldwork, remote-sensing studies, geodetic and geophysical measurements, analytical, analogue and numerical simulations, and laboratory studies of volcanic rocks.
Studies may be focused at the regional scale, investigating the tectonic setting responsible for and controlling volcanic activity, both along divergent and convergent plate boundaries, as well in intraplate settings. At a more local scale, all types of surface deformation in volcanic areas are of interest, such as elastic inflation and deflation, or anelastic processes, including caldera and flank collapses. Deeper, sub-volcanic deformation studies, concerning the emplacement of intrusions, as sills, dikes and laccoliths, are most welcome.
We also particularly welcome geophysical data aimed at understanding magmatic processes during volcano unrest. These include geodetic studies obtained mainly through GPS and InSAR, as well as at their modelling to imagine sources.


The session includes, but is not restricted to, the following topics:
• volcanism and regional tectonics;
• formation of magma chambers, laccoliths, and other intrusions;
• dyke and sill propagation, emplacement, and arrest;
• earthquakes and eruptions;
• caldera collapse, resurgence, and unrest;
• flank collapse;
• volcano deformation monitoring;
• volcano deformation and hazard mitigation;
• volcano unrest;
• mechanical properties of rocks in volcanic areas.

Developing physical-mathematical models able to describe the evolution of eruptive phenomena is a key point in volcanology. In the case of high-risk phenomena, such as lava flows or ash dispersal, predicting their spatial and temporal evolution and determining the potentially affected areas is fundamental in supporting every action directed at mitigating the risk as well as for environmental planning. This session aims to address unresolved challenging questions related to complex geophysical flow modeling and simulation, gathering physical-mathematical models, numerical methods and field and satellite data analysis in order to: (i) expand knowledge of complex volcanic processes and their space-time dynamics; (ii) monitor and model volcanic phenomena; (iii) evaluate model robustness through validation against real case studies, analytical solutions and laboratory experiments; (iv) quantify the uncertainty propagation through both forward (sensitivity analyses) and inverse (optimization/calibration) modelling in all components of volcanic hazard modelling in response to eruptive crises.

Over the past few years, major technological advances allowed to significantly increase both the spatial coverage and frequency bandwidth of multi-disciplinary observations at active volcanoes. Networks of instruments for the quantitative measurement of many parameters now permit an unprecedented, multi-parameter vision of the surface manifestations of mass transport beneath volcanoes. Furthermore, new models and processing techniques have led to innovative paradigms for inverting observational data to image the structures and interpret the dynamics of volcanoes. Within this context, this session aims at bringing together a multidisciplinary audience to discuss the most recent innovations in volcano imaging and monitoring, and to present observations, methods and models that increase our understanding of volcanic processes. New attention has recently been paid to quiescent volcanoes since multidisciplinary investigations showed that magma accumulation at depth can contribute to degassing of volatiles for a long time after the last activity, highlighting the risk of reactivation after a long phase of inactivity. Furthermore, mantle degassing and magma accumulation in continental regions far from volcanism might play an active role in seismicity.
We welcome contributions (1) related to methodological and instrumental advances in geophysical, geological and geochemical imaging of volcanoes, and (2) to explore new knowledge provided by these studies on the internal structure and physical processes of volcanic systems.
We invite contributors from all geophysical, geological and geochemical disciplines such as seismology, electromagnetics, geoelectrics, gravimetry, magnetics, muon tomography, volatile measurements and analysis; from in-situ monitoring networks to high resolution remote sensing and innovative processing methods, applied to volcanic systems ranging from near-surface hydrothermal activity to magmatic processes at depth. We hope in this way to highlight the scientific advances available through the combination of these complementary research areas and to encourage future collaborative efforts.

Glaciers and volcanoes interact in a number of ways, including instances where volcanic/geothermal activity alters glacier dynamics or mass balance, via subglacial eruptions or the deposition of supraglacial tephra. Glaciers can also impact volcanism, for example by directly influencing mechanisms of individual eruptions resulting in the construction of distinct edifices. Glaciers may also influence patterns of eruptive activity when mass balance changes adjust the load on volcanic systems, the water resources and hydrothermal systems. However, because of the remoteness of many glacio-volcanic environments, these interactions remain poorly understood.
In these complex settings, hazards associated with glacier-volcano interaction can vary from lava flows to volcanic ash, lahars, landslides, pyroclastic flows or glacial outburst floods. These can happen consecutively or simultaneously and affect not only the earth, but also glaciers, rivers and the atmosphere. As accumulating, melting, ripping or drifting glaciers generate signals as well as degassing, inflating/ deflating or erupting volcanoes, the challenge is to study, understand and ultimately discriminate these potentially coexisting signals. We wish to fully include geophysical observations of current and recent events with geological observations and interpretations of deposits of past events. Glaciovolcanoes also often preserve a unique record of the glacial or non-glacial eruptive environment that is capable of significantly advancing our knowledge of how Earth's climate system evolves.
We invite contributions that deal with the mitigation of the hazards associated with ice-covered volcanoes in the Arctic, Antarctic or globally, that improve the understanding of signals generated by ice-covered volcanoes, or studies focused on volcanic impacts on glaciers and vice versa. Research on recent activity is especially welcomed. This includes geological observations e.g. of deposits in the field or remote-sensing data, together with experimental and modelling approaches. We also invite contributions from any part of the world on past activity, glaciovolcanic deposits and studies that address climate and environmental change through glaciovolcanic studies. We aim to bring together scientists from volcanology, glaciology, seismology, geodesy, hydrology, geomorphology and atmospheric science in order to enable a broad discussion and interaction.

Magmatic processes occurring at depth within magmatic plumbing systems are complex and play a fundamental role in controlling the tempo and style of volcanic activity, the formation of cumulate rocks and the generation of orthomagmatic and magmatic-hydrothermal ore deposits. To unravel the complexity and temporal evolution of magmatic plumbing systems a multidisciplinary approach is necessary. This session aims to bring together scientists working on the understanding of the structural, chemical and temporal evolution of magmatic systems using, for example, fieldwork, petrology, geochemistry, geophysics, geodesy, experiments or numerical modelling to diffuse the boundaries between disciplines and lead to a comprehensive understanding of the inner workings of Volcanic and Igneous Plumbing Systems (VIPS).

This session is sponsored by the IAVCEI Commission on Volcanic and Igneous Plumbing Systems.

Volcanoes release gas effluents and aerosol particles into the atmosphere during eruptive episodes and by quiescent emissions. Volcanic degassing exerts a dominant role in forcing the timing and nature of volcanic unrest and eruptions. Understanding the exsolution processes of gas species dissolved in magma, and measuring their emissions is crucial to characterise eruptive mechanism and evaluate the sub-sequent impacts on the atmospheric composition, the environment and the biosphere. Emissions range from silent exhalation through soils to astonishing eruptive clouds that release gas and particles into the atmosphere, potentially exerting a strong impact on the Earth’s radiation budget and climate over a range of temporal and spatial scales. Strong explosive volcanic eruptions are a major natural driver of climate variability at interannual to multidecadal time scales. Quiescent passive degassing and smaller-magnitude eruptions on the other hand can impact on regional climate system. Through direct exposure and indirect effects, volcanic emissions may influence local-to-regional air quality and seriously affect the biosphere and environment. Volcanic gases can also present significant hazards to populations downwind of an eruption, in terms of human, animal and plant health, which subsequently can affect livelihoods and cause socio-economic challenges. Gas emissions are measured and monitored via a range of in-situ and remote sensing techniques, to gain insights into both the subterranean-surface processes and quantify the extent of their impacts. In addition, modelling of the subsurface and atmospheric/climatic processes, as well as laboratory experiments, are fundamental to the interpretation of field-based and satellite observations.

This session focuses on the state-of-the-art and interdisciplinary science concerning all aspects of volcanic degassing and impacts of relevance to the Volcanology, Environmental, Atmospheric and Climate sciences (including regional climate), and Hazard assessment. We invite contributions on all aspects of volcanic plumes science, their observation, modelling and impacts. We welcome contributions that address issues around the assessment of hazards and impacts from volcanic degassing both in crises and at persistently degassing volcanoes.

Volcanic aerosol clouds from major tropical eruptions cause periods of strong surface cooling in the historical climate record and are dominant influences within decadal surface temperature trends.

Even the transition from the unusual 1998-2002 period of a “fully decayed to quiescence” stratospheric aerosol layer, into a more typical period of modest volcanic activity temporarily offset a substantial proportion of the subsequent decadal forcing from increased greenhouse gases.

Advancing our understanding of the influence of volcanoes on climate relies upon better knowledge of (i) the radiative forcings of past eruptions and the microphysical, chemical and dynamical processes which affect the evolution of stratospheric aerosol properties and (ii) the response mechanisms governing post-eruption climate variability and their dependency on the climate state at the time of the eruption. This can only be achieved by combining information from satellite and in-situ observations of recent eruptions, stratospheric aerosol and climate modelling activities, and reconstructions of past volcanic histories and post-eruption climate state from proxies.

In recent years the smoke from intense wildfires in North America and Australia has also been an important component of the stratospheric aerosol layer, the presence of organic aerosol and meteoric particles in background conditions now also firmly established.

This session seeks presentations from research aimed at better understanding the stratospheric aerosol layer, its volcanic perturbations and the associated impacts on climate through the post-industrial period (1750-present) and also those further back in the historical record.

We also welcome contributions to understand the societal impacts of volcanic eruptions and the human responses to them. Contributions addressing volcanic influences on atmospheric composition, such as changes in stratospheric water vapour, ozone and other trace gases are also encouraged.

The session aims to bring together research contributing to several current international co-ordinated activities: SPARC-SSiRC, CMIP6-VolMIP, CMIP6-PMIP, and PAGES-VICS.

Extreme convective events are increasing in northern and eastern Europe in frequency and intensity accounting for major economic damages related to natural disasters in several countries. Forecasting the land convection locally developed in a short time range is very challenging since the models are not able to resolve them and this is an issue for the air traffic management.

In recent years, attention was paid to the detection and monitoring of volcanic clouds as their impact on the European air traffic control system was unprecedented (e.g. Eyjafjallajökull 2010 eruption). Volcanic clouds are very dangerous for the aviation operations 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 Convective and Volcanic Clouds (CVC) 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, forecasting and modeling the CVC, to develop early warning systems and to support end-users (such as air traffic managers and pilots) and policy makers. Furthermore, there is a need for improved information exchange regarding the impact of the CVC on daily aviation operations. In this regard, we will draw on the work of the Single European Sky ATM Research (SESAR) Joint Undertaking, with special focus on the latest funded exploratory research projects dealing with these topics.

The objective of the session is to connect different communities in touch with the CVC and to promote discussions between scientists working in remote sensing, modelers, meteorologists, physicists, sensors engineers, engines manufacturers, pilots and aviation managers, allowing the researchers to understand the end-users’ needs and allowing the end-users to understand the research capabilities.

This session solicits the latest studies from the spectrum of:
- detection, monitoring and modeling of CVC with novel techniques and new sensors,
- forecasting and nowcasting extreme weather events,
- study of the CVC structure,
- understanding the impact of the CVC on air traffic management,
- proposal of new products, tools or services focused on the end-users prospective.

Landslides are ubiquitous geomorphological phenomena with potentially catastrophic consequences. In several countries, landslide mortality can be higher than that of any other natural hazard. Predicting landslides is a difficult task that is of both scientific interest and societal relevance that may help save lives and protect individual properties and collective resources. The session focuses on innovative methods and techniques to predict landslide occurrence, including the location, time, size, destructiveness of individual and multiple slope failures. All landslide types are considered, from fast rockfalls to rapid debris flows, from slow slides to very rapid rock avalanches. All geographical scales are considered, from the local to the global scale. Of interest are contributions investigating theoretical aspects of natural hazard prediction, with emphasis on landslide forecasting, including conceptual, mathematical, physical, statistical, numerical and computational problems, and applied contributions demonstrating, with examples, the possibility or the lack of a possibility to predict individual or multiple landslides, or specific landslide characteristics. Of particular interest are contributions aimed at: the evaluation of the quality of landslide forecasts; the comparison of the performance of different forecasting models; the use of landslide forecasts in operational systems; and investigations of the potential for the exploitation of new or emerging technologies e.g., monitoring, computational, Earth observation technologies, in order to improve our ability to predict landslides. We anticipate that the most relevant contributions will be collected in the special issue of an international journal.

Debris flows are among the most dangerous natural hazards that threaten people and infrastructures in both mountainous and volcanic areas. The study of the initiation and dynamics of debris flows, along with the characterization of the associated erosion/deposition processes, is of paramount importance for hazard assessment, land-use planning and design of mitigation measures, including early warning systems. In addition, the impacts of climate change on debris-flow activity must be considered and carefully analysed, as the number of mountain areas prone to these events may increase in future.
A growing number of scientists with diverse backgrounds are studying debris flows and lahars. The difficulties in measuring parameters related to their initiation and propagation have progressively prompted research into a wide variety of laboratory experiments and monitoring studies. However, there is a need of improving the quality of instrumental observations that would provide knowledge for more accurate hazards maps and modeling. Nowadays, the combination of distributed sensor networks and remote sensing techniques represents a unique opportunity to gather direct observations of debris flows to better constrain their physical properties.
Scientists working in the field of debris flows are invited to present their recent advancements. In addition, contributions from practitioners and decision makers are also welcome. Topics of the session include: field studies and documentation, mechanics of debris-flow initiation and propagation, laboratory experiments, modeling, monitoring, impacts of climate change on debris-flow activity, hazard and risk assessment and mapping, early warning, and alarm systems.