This session will focus on variability in the ocean and its role in the wider climate system using both observations and models. Areas to be considered will include both ocean heat uptake and circulation variability as well as exploring the use of sustained ocean observing efforts and models to make progress in understanding the ocean’s role in the climate system. More than 90% of the excess heat in the climate system has been stored in the ocean, which mitigates the rate of surface warming. Better understanding of ocean ventilation mechanisms, as well as the uptake, transport, and storage of oceanic heat are therefore essential for reducing the uncertainties on global warming projections. Circulation variability and connectivity, particularly from the South Atlantic to the North Atlantic and Arctic Ocean, are also of interest as well as how they are driven by local-, large- or global-scale processes or teleconnections. Sustained observations at sea are being made within a wide variety of programmes and are leading to significant advances in our ability to understand and model climate. Thus, this session will also explore ongoing and planned sustained ocean observing efforts and illuminate their roles in improving understanding of the ocean’s role in the climate system. For example, air-sea flux moorings are being maintained at select sites to assess models and air-sea flux fields. Deep temperature and salinity measurements are being made at time series moorings and will be made by deep Argo floats. Significant advances are also being made using Argo floats for biogeochemistry and carbon measurements. Such observations provide the means to develop linkages between sustained ocean observing and climate modelling. In conclusion, the session will consider key aspects of ocean variability and its climate relevance, as well as encouraging the use of observations and models to enhance understanding of these areas.

The ocean surface mixed layer mediates the transfer of heat, freshwater, momentum and trace gases between atmosphere, sea ice and ocean, thus playing a central role in the dynamics of our climate. This session will focus on the surface mixed layer globally, from the coastal ocean to the deep ocean. We will review recent progress in understanding the key dynamical and biogeochemical processes taking place in the mixed layer: surface waves, Langmuir circulations and turbulence, shear-induced mixing, internal waves, coherent structures, fronts, frontal instabilities, entrainment and detrainment at the mixed layer base, convection, restratification, dynamics of the euphotic layer, carbon and nutrient cycling, etc. The improvement of the representation of surface mixed layer processes in numerical models is a complex and pressing issue: this session will bring together new advances in the representation of mixed layer processes in high resolution numerical models, as well as evaluation of mixed layer properties in climate models using most recent observational datasets. The coupling of the ocean and atmospheric boundary layers as well as the special processes occurring under sea ice and in the marginal sea ice zone will be given special consideration. This session welcomes all contributions related to the study of the oceanic mixed layer independent of the time- and space scales considered. This includes small scale process studies, short-term forecasting of the mixed layer characteristics for operational needs, studies on the variability of the mixed layer from sub-seasonal to multi annual time scales and mixed layer response to external forcing. The use of multiple approaches (coupled numerical modeling, reanalyses, observations) is encouraged.

Ocean ventilation is a process by which water properties imprinted by the atmosphere onto the upper ocean, such as oxygen, carbon dioxide and trace gases, are transported into the ocean interior. In mediating the exchange between the atmosphere and the ocean, ventilation plays an important role in both climate variability and biogeochemical cycles. This is manifested, for example, through the supply of oxygen to the ocean interior, transport and sequestration of nutrients, and the uptake and storage of anthropogenic carbon and heat in the ocean interior. Increased stratification - caused by the warming on the upper ocean under climate change - could lead to a reduction of ocean ventilation over the coming decades. However, the mechanism by which the changes in ocean ventilation will emerge, and their consequences for climate feedback, biogeochemical processes, and ocean ecosystems are not well known.

Developing our understanding of ocean ventilation is inhibited by the wide range of spatial scales inherent in the process, from small-scale mixing to basin scale. Robust projection of future change requires deeper insight into the processes driving ventilation, the spatial and temporal variability of ventilation, and the consequences and impacts of ventilation changes.

We invite contributions that advance understanding on the broad topic of ocean ventilation, its potential to change in a warming climate, and the consequences therein. We seek contributions that investigate both the physical processes involved in ocean ventilation — from small-scale mixing, to mesoscale stirring, to basin scale subduction — as well as the consequences for biogeochemical cycles and marine ecosystems. We welcome contributions from process-oriented studies as well as those that assess and quantify variability and projected changes, and welcome studies making use of observations, theory and/or numerical model.

The session is expected to be in a hybrid format, partly taking place in Vienna in a traditional format, and partly online.

Theoretical and model studies show that the ocean is a chaotic system which spontaneously generates a strong, multi-scale intrinsic chaotic variability: uncertainties in ocean model initial states may grow and strongly affect the simulated variability up to multi-decadal and basin scales, with or without coupling to the atmosphere. In addition, ocean simulations require both the use of subgrid-scale parameterizations that crudely mimic unresolved processes, and the calibration of the parameters associated with these parameterizations. In this context of multiple uncertainties, oceanographers are increasingly adopting ensemble simulation strategies, probabilistic analysis methods, and developing stochastic parameterizations for modeling and understanding ocean variability.

Presentations are solicited about the conception and analysis of ocean ensemble simulations, the characterization of ocean model uncertainties, and the development of stochastic parameterizations for ocean models. The session will also cover the dynamics and structure of chaotic ocean variability, its relationship with atmospheric variability, and the use of dynamical system or information theories for the investigation of oceanic variability. We welcome as well studies about the propagation of chaotic ocean variability towards other components of the climate system, about its consequences regarding ocean predictability, operational forecasts, detection and attribution of climate signals, climate simulations and projections.

The rapid decline of the Arctic sea ice in the last decade is a dramatic indicator of climate change. The Arctic sea ice cover is now thinner, weaker and drifts faster. Freak heatwaves are common. On land, the permafrost is dramatically thawing, glaciers are disappearing, and forest fires are raging. The ocean is also changing: the volume of freshwater stored in the Arctic has increased as have the inputs of coastal runoff from Siberia and Greenland and the exchanges with the Atlantic and Pacific Oceans. As the global surface temperature rises, the Arctic Ocean is speculated to become seasonally ice-free by the mid 21st century, which prompts us to revisit our perceptions of the Arctic system as a whole. What could the Arctic Ocean look like in the future? How are the present changes in the Arctic going to affect and be affected by the lower latitudes? What aspects of the changing Arctic should observational, remote sensing and modelling programmes address in priority?

In this session, we invite contributions from a variety of studies on the recent past, present and future Arctic. We encourage submissions examining interactions between the ocean, atmosphere and sea ice, on emerging mechanisms and feedbacks in the Arctic and on how the Arctic influences the global ocean. Submissions taking a cross-disciplinary, system approach and focussing on emerging cryospheric, oceanic and biogeochemical processes and their links with land are particularly welcome.

The session supports the actions of the United Nations Decade of Ocean Science for Sustainable Development (2021-2030) towards addressing challenges for sustainable development in the Arctic and its diverse regions. We aim to promote discussions on the future plans for Arctic Ocean modelling and measurement strategies, and encourages submissions on the results from IPCC CMIP and the recent observational programs, such as the Multidisciplinary drifting Observatory for the Study of Arctic Climate (MOSAiC). This session is cosponsored by the CLIVAR /CliC Northern Ocean Regional Panel (NORP) that aims to facilitate progress and identify scientific opportunities in (sub)Arctic ocean-sea-ice-atmosphere research.

Drs Karen Assmann and Wilken-Jon von Appen are the solicited speakers for the session. Karen Assmann will be presenting on physical and ecological implications of Arctic Atlantification. Wilken-Jon von Appen will be talking about eddies in the Arctic Ocean.

The North Atlantic exhibits a high level of natural variability from interannual to centennial time scales, making it difficult to extract trends from observational time series. Climate models, however, predict major changes in this region, which in turn will influence sea level and climate, especially in western Europe and North America. In the last years, several observational projects have been focused on the Atlantic circulation changes, for instance ACSIS, RACE, RAPID, OSNAP, and OVIDE. Another important issue is the interaction between the atmosphere and the ocean as well as the cryosphere with the ocean, and how this affects the climate.

We welcome contributions from observers and modelers on the following topics:

-- climate relevant processes in the North Atlantic region in the atmosphere, ocean, and cryosphere
-- response of the atmosphere to changes in the North Atlantic
-- atmosphere - ocean coupling in the North Atlantic realm on time scales from years to centuries (observations, theory and coupled GCMs)
-- interpretation of observed variability in the atmosphere and the ocean in the North Atlantic sector
-- comparison of observed and simulated climate variability in the North Atlantic sector and Europe
-- dynamics of the Atlantic meridional overturning circulation
-- variability in the ocean and the atmosphere in the North Atlantic sector on a broad range of time scales
-- changes in adjacent seas related to changes in the North Atlantic
-- role of water mass transformation and circulation changes on anthropogenic carbon and other parameters
-- linkage between the observational records and proxies from the recent past

Observations and model simulations illustrate significant ocean variability and associated air-sea interactions in the tropical Atlantic basin from daily-to-decadal time scales. This session is devoted to the understanding of ocean dynamics in the tropical and subtropical Atlantic Ocean, its interaction with the overlying atmosphere from the equator to the mid-latitudes and its climate impacts on adjacent to remote areas. Relevant processes in the ocean include upper and deep ocean circulation, eddies, tropical instability waves, warm pools, cold tongues and eastern boundary upwellings. We are interested in air-sea interactions related to both the seasonal cycle and the development of modes of variability from local to basin scale (e.g. the Meridional Mode, the Atlantic Niño, and the Benguela Niño). We welcome studies on wind variations related to the development of these modes, as well as studies on high-frequency events, such as marine heat waves, the Madden-Julian Oscillation, tropical cyclones and convective systems. Furthermore, we seek studies on climate change in the region, and also of the climatic impacts of change and variability on marine ecosystems. Finally, we are also interested in contributions examining the causes and impacts of systematic model errors in simulating the local to regional Atlantic climate. Studies based on direct observations, reanalysis, reconstructions as well as model simulations are welcome.

The Indian Ocean is unique among the other tropical ocean basins due to the seasonal reversal of monsoon winds and concurrent ocean currents, lack of steady easterlies that result in a relatively deep thermocline along the equator, low-latitude connection to the neighboring Pacific and a lack of northward heat export due to the Asian continent. These characteristics shape the Indian Ocean’s air-sea interactions, variability, as well as its impacts and predictability in tropical and extratropical regions on (intra)seasonal, interannual, and decadal timescales. They also make the basin particularly vulnerable to anthropogenic climate change, as well as related extreme weather and climate events, and their impacts for surrounding regions, which are home to a third of the global population. Advances have recently been made in our understanding of the Indian Ocean’s circulation, interactions with adjacent ocean basins, and its role in regional and global climate. Nonetheless, significant gaps remain in understanding, observing, modeling, and predicting Indian Ocean variability and change across a range of timescales.

This session invites contributions based on observations, modelling, theory, and palaeo proxy reconstructions in the Indian Ocean that focus on recent observed and projected changes in Indian Ocean physical and biogeochemical properties and their impacts on ecological processes, diversity in Indian Ocean modes of variability (e.g., Indian Ocean Dipole, Indian Ocean Basin Mode, Madden-Julian Oscillation) and their impact on predictions, interactions and exchanges between the Indian Ocean and other ocean basins, as well as links between Indian Ocean variability and monsoon systems across a range of timescales. In particular, we encourage submissions on weather and climate extremes in the Indian Ocean, including marine heatwaves and their ecological impacts. We also welcome contributions that address research on the Indian Ocean grand challenges highlighted in the recent IndOOS Decadal Review, and as formulated by the Climate and Ocean: Variability, Predictability, and Change (CLIVAR), the Sustained Indian Ocean Biogeochemistry and Ecosystem Research (SIBER), the International Indian Ocean Expedition 2 (IIOE-2), findings informed by the Coupled Model Intercomparison Project version 6 (CMIP6) on past, present and future variability and change in the Indian Ocean climate system, and contributions making use of novel methodologies such as machine learning.

The Southern Ocean around the latitudes of the Antarctic Circumpolar Current is vital to our understanding of the climate system. It is a key region for vertical and lateral exchanges of heat, carbon, and nutrients, with significant past and potential future global climate implications. The role of the Southern Ocean as a dominant player in heat and carbon exchanges in present and future climate conditions remains uncertain. Indeed, the lack of observations of this system and its inherent sensitivity to small-scale physical processes, not fully represented in current Earth system models, result in large climate projection uncertainties. To address these knowledge gaps, the Southern Ocean has been the subject of recent observational, theoretical, and numerical modelling investigations. These efforts are providing deeper insight into the three-dimensional patterns of Southern Ocean change on sub-annual, multi-decadal and millennial timescales. In this session, we will discuss the current state of knowledge and novel findings concerning the role of the Southern Ocean in past, present, and future climates. These include (but are not limited to) small-scale physics and mixing, water mass transformation, gyre-scale processes, nutrient and carbon cycling, ocean productivity, climate-carbon feedbacks, and ocean-ice-atmosphere interactions. We will also discuss how changes in Southern Ocean heat and carbon transport affect lower latitudes and global climate more generally.

The interaction between the ocean and the cryosphere in the Southern Ocean has become a major focus in climate research. Antarctic climate change has captured public attention, which has spawned a number of research questions, such as: Is Antarctic sea ice becoming more vulnerable in a changing climate? Where and when will melting of ice shelves by warm ocean waters yield a tipping point in Antarctic climate? What role do ice-related processes play in nutrient upwelling on the continental shelf and in triggering carbon export to deep waters? Recent advances in observational technology, data coverage, and modeling provide scientists with a better understanding of the mechanisms involving ice-ocean interactions in the far South. Processes on the Antarctic continental shelf have been identified as missing links between the cryosphere, the global atmosphere and the deep open ocean that need to be captured in large-scale and global model simulations.

This session calls for studies on physical and biogeochemical interactions between ice shelves, sea ice and the ocean. The ice-covered Southern Ocean and its role in the greater Antarctic climate system are of major interest. This includes work on all scales, from local to basin-scale to circumpolar. Studies based on in-situ observations and remote sensing as well as regional to global models are welcome. We particularly invite cross-disciplinary topics involving physical and biological oceanography, glaciology or biogeochemistry.

The Open Session on atmosphere, land and ocean monitoring aims at presenting highlights of recent results obtained through observations and modelling as well as relevant reviews in these fields.
We shall connect with Earth Observations programmes at ESA, EU and worldwide, using new satellites and oberving platforms, as well as new techniques for distributing, merging and analysing EO data using AI.

The session is intended as an open forum for interdisciplinary discussion between representatives of different fields. Thus, we welcome especially overarching presentations which may be interesting to a wider community.

Observations are one major link to get an overall picture of processes within the Earth environment during measurement campaigns. This includes application to derive atmospheric parameters, surface properties of vegetation, soil and minerals and dissolved or suspended matter in inland water and the ocean. Ground based systems and data sets from ships, aircraft and satellites are key information sources to complement the overall view. All of these systems have their pros and cons, but a comprehensive view of the observed system is generally best obtained by means of a combination of all of them.

The validation of operational satellite systems and applications is a topic that has come increasingly into focus with the European Copernicus program in recent years. The development of smaller state-of-the-art instruments, the combination of more and more complex sets of instruments simultaneously on one platform, with improved accuracy and high data acquisition speed together with high accuracy navigation and inertial measurements enables more complex campaign strategies even on smaller aircraft or unmanned aerial vehicles (UAV).

This session will bring together a multidisciplinary research community to present:

• Atmosphere-land-ocean (or inland water) system modelling and validation
• new instruments (Lidar, etc), platforms (UAV etc.), setups and use in multidisciplinary approaches
• Larger scale in-situ and remote sensing observation networks from various platforms (ground based, airborne, ship-borne, satellite)
• recent field campaigns and their outcomes
• (multi-) aircraft campaigns
• satellite calibration/validation campaigns
• sophisticated instrument setups and observations
• advanced instrument developments
• UAV applications

The largest single source of uncertainty in projections of future global sea level is associated with the mass balance of the Antarctic Ice Sheet (AIS). In the short-term, it cannot be stated with certainty whether the mass balance of the AIS is positive or negative; in the long-term, the possibility exists that melting of the coastal shelves around Antarctica will lead to an irreversible commitment to ongoing sea level rise. Observational and paleoclimate studies can help to reduce this uncertainty, constraining the parameterizations of physical processes within ice sheet models and allowing for improved projections of future global sea level rise. This session welcomes presentations covering all aspects of observation, paleoclimate reconstruction and modeling of the AIS. Presentations that focus on the mass balance of the AIS and its contribution towards changes in global sea level are particularly encouraged.

In recent decades, the climate in the polar regions has undergone dramatic changes. Quantifying the individual contributions of Earth system components (cryosphere, ocean, atmosphere, and land) to the observed changes is challenging due to feedback between the components. Examples include (but are not limited to) ice shelf-ocean interactions (through basal melting and cavity geometry evolution) and elevation feedbacks (through surface mass balance). Hence, studies based on individual components of the Earth System have limited capacity to represent all relevant processes. This session aims to provide a platform for sharing coupled modelling experiences incorporating the cryosphere in the polar regions.

Before obtaining scientific outcomes, design decisions must be made in the development of coupled models. Adopting existing coupling technologies or implementing new, concurrent or sequential parallelism, bringing component source codes together or maintaining independence, choosing the level of temporal synchronicity between components operating on different timescales, are all examples of choices to be made.
We solicit both technical and scientific contributions from modelling studies in which feedback and emergent properties between the cryosphere and other Earth System components in polar regions are investigated, better understood, and possibly even quantified. In addition to application of coupled modelling to real world domains, contributions are also invited from idealised studies and intercomparisons, such as the Marine Ice Sheet-Ocean Intercomparison Project (MISOMIP).

Machine learning, artificial intelligence and big data approaches have recently emerged as key tools in understanding the cryosphere. These approaches are being increasingly applied to answer long standing questions in cryospheric science, including those relating to remote sensing, forecasting, and improving process understanding across Antarctic, Arctic and Alpine regions. In doing so, data science and AI techniques are being used to gain insight into system complexity, analyse data on unprecedented temporal and spatial scales, and explore much wider parameter spaces than were previously possible.
In this session we invite submissions that utilise data science and/or AI techniques that address research questions relating to glaciology, sea ice, permafrost and/or polar climate science. Approaches used may include (but are not limited to) machine learning, artificial intelligence, big data processing/automation techniques, advanced statistics, and innovative software/computing solutions. These could be applied to any (or combinations) of data sources including remote sensing, numerical model output and field/lab observations. We particularly invite contributions that apply techniques and approaches that reveal new insights into cryospheric research problems that would not otherwise be achievable using traditional methods, and those that discuss how or if approaches can be applied or adapted to other areas of cryospheric science. Given the rapid development of this field by a diverse group of international researchers, we convene this session to help foster future collaboration amongst session contributors, attendees, and international stakeholders and help address the most challenging questions in cryospheric science.

Ice sheets play an active role in the climate system by amplifying, pacing, and potentially driving global climate change over a wide range of time scales. The impact of interactions between ice sheets and climate include changes in atmospheric and ocean temperatures and circulation, global biogeochemical cycles, the global hydrological cycle, vegetation, sea level, and land-surface albedo, which in turn cause additional feedbacks in the climate system. This session will present data and modelling results that examine ice sheet interactions with other components of the climate system over several time scales. Among other topics, issues to be addressed in this session include ice sheet-climate interactions from glacial-interglacial to millennial and centennial time scales, the role of ice sheets in Cenozoic global cooling and the mid-Pleistocene transition, reconstructions of past ice sheets and sea level, the current and future evolution of the ice sheets, and the role of ice sheets in abrupt climate change.

Ice shelves and tidewater glaciers are sensitive elements of the climate system. Sandwiched between atmosphere and ocean, they are vulnerable to changes in either. The recent disintegration of ice shelves such as Larsen B and Wilkins on the Antarctic Peninsula, current thinning of the ice shelves in the Amundsen Sea sector of West Antarctica, and the recent accelerations of many of Greenland's tidewater glaciers provide evidence of the rapidity with which those systems can respond. Changes in marine-terminating outlets appear to be intimately linked with acceleration and thinning of the ice sheets inland of the grounding line, with immediate consequences for global sea level. Studies of the dynamics and structure of the ice sheets' marine termini and their interactions with atmosphere and ocean are the key to improving our understanding of their response to climate forcing and of their buttressing role for ice streams. The main themes of this session are the dynamics of ice shelves and tidewater glaciers and their interaction with the ocean, atmosphere and the inland ice, including grounding line dynamics. The session includes studies on related processes such as calving, ice fracture, rifting and mass balance, as well as theoretical descriptions of mechanical and thermodynamic processes. We seek contributions both from numerical modelling of ice shelves and tidewater glaciers, including their oceanic and atmospheric environments, and from observational studies of those systems, including glaciological and oceanographic field measurements, as well as remote sensing and laboratory studies.

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 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 the different time horizons 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, exploration of artificial-intelligence methods, etc.
Following the new WCRP 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 between atmosphere, land, ocean, and sea-ice components, as well as the impacts of coupling and feedbacks in physical, chemical, biological, and human dimensions. 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.
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.

To address societal concerns over rising sea level and extreme events, understanding the contributions behind these changes is key to predict potential impacts of sea level change on coastal communities and global economy, and is recognized as one of the Grand Challenges of our time by the World Climate Research Programme (WCRP). To continue this discussion, we welcome contributions from the international sea level community that improve our knowledge of the past and present changes in global and regional sea level, extreme events, and flooding, and produce improved predictions of their future changes.

We welcome studies on various drivers of sea level change and linkages between variability in sea level, heat and freshwater content, ocean dynamics, land subsidence from natural versus anthropogenic influences, and mass exchange between the land and the ocean associated with ice sheet and glacier mass loss and changes in the terrestrial water storage. Studies focusing on future sea level changes are also encouraged, as well as those discussing potential short-, medium-, and long-term impacts on coastal and deltaic environments, as well as the global oceans.

ENSO and its interactions with other tropical basins are the dominant source of interannual climate variability in the tropics and across the globe. Understanding the dynamics, predictability, and impacts of ENSO and tropical basins interactions, and anticipating their future changes are thus of vital importance for society. This session invites contributions regarding all aspects of ENSO and tropical basins interactions, including: dynamics, multi-scale interactions; low frequency, decadal and paleo variability; theoretical approaches; ENSO diversity; global teleconnections; impacts on climate, society and ecosystems; seasonal forecasting and climate change projections of ENSO and its tropical basins interactions. Studies aimed at evaluating and improving model simulations of ENSO, the tropical mean state and the tropical basins interactions basin are especially welcomed.

This session aims to place recently observed climate change in a long-term perspective by highlighting the importance of paleoclimate research spanning the past 2000 years. We invite presentations that provide insights into past climate variability, over decadal to millennial timescales, from different paleoclimate archives (ice cores, marine sediments, terrestrial records, historical archives and more). In particular, we are focussing on quantitative temperature and hydroclimate reconstructions, and reconstructions of large-scale modes of climate variability from local to global scales. This session also encourages presentations on the attribution of past climate variability to external drivers or internal climate processes, data syntheses, model-data comparison exercises, proxy system modelling, and novel approaches to producing multi-proxy climate field reconstructions.

Predictions of climate from seasonal to decadal timescales and their applications are 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 developing and evaluating new applications and climate services.

The session covers dynamical as well as statistical predictions (including machine learning methods) and their combination. It investigates predictions of various climate phenomena, including extremes, from global to regional scales, and from seasonal to multi-decadal timescales ("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 are discussed, as are observational and emergent constraints on climate variability and predictability. Also, the time-dependence of the predictive skill, or windows of opportunity (hindcast period), are investigated. Analysis of predictions in a multi-model framework, and ensemble forecast initialization and generation, including innovative ensemble approaches to minimize initialization shocks, are another focus of the session. The session pays 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.

In 2015, the UN Sustainable Development Goals and the Paris Agreement on climate recognized the deteriorating resilience of the Earth system, with planetary-scale human impacts constituting a new geological epoch: the Anthropocene. Earth system resilience critically depends on the nonlinear interplay of positive and negative feedbacks of biophysical and increasingly also socio-economic processes. These include dynamics and interactions between the carbon cycle, the atmosphere, oceans, large-scale ecosystems, and the cryosphere, as well as the dynamics and perturbations associated with human activities.

With rising anthropogenic pressures, there is an increasing risk we might be hitting the ceiling of some of the self-regulating feedbacks of the Earth System, and cross tipping points which could trigger large-scale and partly irreversible impacts on the environment, and impact the livelihood of millions of people. Potential domino effects or tipping cascades could arise due to the interactions between these tipping elements and lead to a further decline of Earth resilience. At the same time, there is growing evidence supporting the potential of positive (social) tipping points that could propel rapid decarbonization and transformative change towards global sustainability.

In this session we invite contributions on all topics relating to tipping points in the Earth system, positive (social) tipping, as well as their interaction and domino effects. We are particularly interested in various methodological approaches, from Earth system modelling to conceptual modelling and data analysis of nonlinearities, tipping points and abrupt shifts in the Earth system.

An increasing number of single model large ensemble simulations from Global Climate Models (GCM), Earth System Models (ESM), or Regional Climate Models (RCM) have been generated over recent years, to investigate internal variability and forced changes of the climate system — and to aid the interpretation of the observational record by providing a range of historical climate trajectories that could have been. The increased availability of large ensembles also enables new and inter-disciplinary applications beyond large-scale climate dynamics.

This session invites studies using large GCM, ESM, or RCM ensembles looking at the following topics: 1) Reinterpretation of the observed record in light of internal variability; 2) forced changes in internal variability; 3) development of new approaches to attribute and study observed events or trends; 4) impacts of natural climate variability; 5) assessment of extreme and compound event occurrence; 6) combining single model large ensembles with CMIP archives for robust decision making; 7) large ensembles as testbeds for method development.

We welcome research across all components of the Earth system. Examples include topics ranging from climate dynamics, hydrology and biogeochemistry to research on the role of internal variability in impact studies, focused for example on agriculture, air pollution or energy generation and consumption. We particularly invite studies that apply novel methods or cross-disciplinary approaches to leverage the potential of large ensembles.

Modelling past climate states, and the transient evolution of Earth’s climate remains challenging. Time periods such as the Paleocene, Eocene, Pliocene, the Last Interglacial, the Last Glacial Maximum or the mid-Holocene span across a vast range of climate conditions. At times, these lie far outside the bounds of the historical period that most models are designed and tuned to reproduce. However, our ability to predict future climate conditions and potential pathways to them is dependent on our models' abilities to reproduce just such phenomena. Thus, our climatic and environmental history is ideally suited to thoroughly test and evaluate models against data, so they may be better able to simulate the present and make future climate projections.

We invite papers on palaeoclimate-specific model development, model simulations and model-data comparison studies. Simulations may be targeted to address specific questions or follow specified protocols (as in the Paleoclimate Modelling Intercomparison Project – PMIP or the Deep Time Model Intercomparison Project – DeepMIP). They may include anything between time-slice equilibrium experiments to long transient climate simulations (e.g. transient simulations covering the entire glacial cycle as per the goal of the PalMod project) with timescales of processes ranging from synoptic scales to glacial cycles and beyond. Comparisons may include past, historical as well as future simulations and focus on comparisons of mean states, gradients, circulation or modes of variability using reconstructions of temperature, precipitation, vegetation or tracer species (e.g. δ18O, δD or Pa/Th).

Evaluations of results from the latest phase of PMIP4-CMIP6 are particularly encouraged. However, we also solicit comparisons of different models (comprehensive GCMs, isotope-enabled models, EMICs and/or conceptual models) between different periods, or between models and data, including an analysis of the underlying mechanisms as well as contributions introducing novel model or experimental setups.

The dynamics of the Earth system and its components is highly nonlinear. In particular, several subsystems have been suggested to react abruptly at critical levels of anthropogenic forcing. Well-known examples of such Tipping Elements include the Atlantic Meridional Overturning Circulation, the polar ice sheets and sea ice, tropical and boreal forests, as well as the Asian monsoon systems. Interactions between the different Tipping Elements may either have stabilizing or destabilizing effects on the other subsystems, potentially leading to cascades of abrupt transitions. The critical forcing levels at which abrupt transitions occur have recently been associated with Tipping Points.

It is paramount to determine the critical forcing levels (and the associated uncertainties) beyond which the systems in question will abruptly change their state, with potentially devastating climatic, ecological, and societal impacts. For this purpose, we need to substantially enhance our understanding of the dynamics of the Tipping Elements and their interactions, on the basis of paleoclimatic evidence, present-day observations, and models spanning the entire hierarchy of complexity. Moreover, to be able to mitigate - or prepare for - potential future transitions, early warning signals have to be identified and monitored in both observations and models.

This multidisciplinary session invites contributions that address Tipping Points in the Earth system from the different perspectives of all relevant disciplines, including

- the mathematical theory of abrupt transitions in (random) dynamical systems,
- paleoclimatic studies of past abrupt transitions,
- data-driven and process-based modelling of past and future transitions,
- early-warning signals
- the implications of abrupt transitions for Climate sensitivity and response,
- ecological and societal impacts, as well as
- decision theory in the presence of uncertain Tipping Point estimates

Analysis of the energy transfers between and within climate components has been at the core of many step changes in the understanding of the climate system. Large-scale atmospheric circulation, hydrological cycle and heat/moisture transports are tightly intertwined through radiative and heat energy absorption and transports that are sensitive to multiple forcings and feedbacks. Cross-equatorial energy exchanges by the ocean and atmosphere couple Hadley Circulation and Atlantic Overturning circulation, modulating the location and intensity of the ITCZ and the amount of precipitation in monsoon regions. In the extra-tropics, Rossby waves affect the distribution of precipitation and eddy activity, shaping the meridional heat transport from the low latitudes towards the Poles through intermittent events of persistent and co-located blockings and the occurrence of extreme heat waves or cold outbreaks. In the ocean, understanding of energy transfers from large-scale circulation to the internal wave field, through mesoscale and submesoscale eddies, is the basis for the development of new parameterizations and significant modelling advances.
We invite submissions addressing the interplay between Earth’s energy exchanges and the general circulation using modeling, theory, and observations. We encourage contributions on the forced response and natural variability of the general circulation, understanding present-day climate and past and future changes, and impacts of global features and change on regional climate.

Arctic sea ice and high latitude atmosphere and oceans have experienced significant changes over the modern observational era. The polar climate is crucial for the Earth’s energy and water budget, and its variability and change have direct socio-economic and ecological impacts. Thus, understanding high-latitude variability and improving predictions of high latitude climate is highly important for society. Long-term variability in ocean and sea ice are the largest sources for predictability in high latitudes. Dynamical model predictions are not yet in the position to provide us with highly accurate predictions of the polar climate. Main reasons for this are the lack of observations in high latitudes, insufficient initialization methods and shortcomings of climate models in representing some of the important climate processes in high latitudes.

This session aims for a better understanding and better representation of the mechanisms that control high latitude variability and predictability of climate in both hemispheres from sub-seasonal to multi-decadal time-scales in past, recent and future climates. Further, the session aims to discuss ongoing efforts to improve climate predictions at high latitudes at various time scales (e.g., usage of additional observations for initialization, improved initialization methods, impact of higher resolution, improved parameterizations, novel verification approaches) and potential teleconnections of high latitude climate with lower latitude climate. We also aim to link polar climate variability and predictions to potential ecological and socio-economic impacts and encourage submissions on this topic.

The session offers the possibility to present results from ongoing projects and research efforts on the topic of high-latitude climate variability and prediction, including, but not limited to, the WMO Year of Polar Prediction (YOPP), NordForsk-project ARCPATH, MOSAiC, and the H2020-projects APPLICATE, INTAROS, BlueAction, and KEPLER.

This session has greatly benefited by the expansion via added contributions from the CL4.11 session on "Arctic climate change: governing mechanisms and global implications" that specifically aims to identify, characterize and quantify the processes and feedbacks that govern amplified Arctic warming and sea ice retreat, and it also addresses the climate impacts on the lower latitudes associated with Arctic changes.

The Arctic Realm is changing rapidly and the fate of the cryosphere, including Arctic sea ice, glaciers and ice caps, is a source of concern. Whereas sea ice variations impact the radiative energy budget, thus playing a role in Arctic amplification, the Greenland Ice Sheet retreat contributes to global sea level rise. Moreover, through various processes linking the atmosphere, ice and ocean, the change in the Arctic realm may modify the atmospheric and ocean circulation at regional to global scales, the freshwater budget of the ocean and deep-water formation as well as the marine and terrestrial ecosystems, including productivity. The processes and feedbacks involved operate on all time scales and it require a range of types of information to understand the processes, drivers and feedbacks involved in Arctic changes, as well as the land-ocean-cryosphere interaction. In this session, we invite contributions from a range of disciplines and across time scales, including observational (satellite and instrumental) data, historical data, geological archives and proxy data, model simulations and forecasts, for the past, present and future climate. The common denominator of these studies will be their focus on a better understanding of mechanisms and feedbacks on short to long time scales that drive Arctic and subarctic changes and their impact on climate, ocean and environmental conditions, at regional to global scales, including possible links to weather and climate outside the Arctic.

Climate change (CC) and ocean degradation (OD) are among the greatest threats to humanity. Climate impacts the ocean in massive ways; the ocean is the climate’s most powerful regulator. Separately or combined, they impact every living being and ecological niche, with poorer communities suffering disproportionately. In turn, flora and fauna (incl humans) are suffering. CC and OD are affecting the cryosphere, biodiversity, and food and water security. Given that humans are the prime cause of this devastating change taking us beyond our planetary boundaries, geoethical issues come to the fore.

The 2020 EGU Declaration of the Significance of Geoscience highlights the need for massive and widespread action to help people around the world to become literate about the changes affecting their and their offsprings’ and communities’ lives. The more people are literate about these changes, the more they can make informed decisions, adapt and mitigate. Previous General Assemblies have addressed climate change literacy (CL). Ocean literacy (OL) has developed strongly in recent years, especially with impetus from the UN Ocean Decade. Ocean-climate literacy (OCL) is an imperative that needs to be addressed massively and urgently, both within and beyond the EGU.

We invite colleagues to submit contributions on any aspects of OCL; this can, of course, include CL (without the ocean) and OL (without the climate). We welcome papers related, eg, to learning processes/experiences, instructional materials, curricular innovation, learning games, citizen initiatives, Ocean Decade activities, evaluation, well-used methods, novel approaches and policies, eg, 1. make OCL an essential component in all subjects and at all levels of education; 2. require all people in positions of responsibility (eg, mayors, teachers, doctors, CEOs, ministers, et al) to pass exams on the basics of climate and/or ocean before taking office. Of particular interest are literacy actions that bring in geoethical dimensions. (If your paper is primarily on geoethics, then a better home is the EGU session on geoethics.) The broad aims of such OCL might include encouraging an intergenerational outlook, developing a sense of the geoethical dimensions of OCL, understanding complexities and implementing solutions.

This session is an opportunity for ECSs, scientists, educators, policy influencers, learning resource developers and other practitioners to share their experience, expertise and research on CL and OL.

The ocean floor hosts a tremendous variety of forms that reflect the action of a range of tectonic, sedimentary, oceanographic and biological processes at multiple spatio-temporal scales. Many such processes are hazards to coastal populations and offshore installations, and their understanding constitutes a key objective of national and international research programmes and IODP expeditions. High quality bathymetry, especially when combined with sub-seafloor and/or seabed measurements, provides an exciting opportunity to integrate the approaches of geomorphology and geophysics, and to extend quantitative geomorphology offshore. 3D seismic reflection data has also given birth to the discipline of seismic geomorphology, which has provided a 4D perspective to continental margin evolution.

This interdisciplinary session aims to examine the causes and consequences of geomorphic processes shaping underwater landscapes, including submarine erosion and depositional processes, submarine landslides and canyons, sediment transfer and deformation, volcanic activity, fluid migration and escape, faulting and folding, and other processes acting at the seafloor. The general goal of the session is to bring together researchers who characterise the shape of past and present seafloor features, seek to understand the sub-surface and surface processes at work and their impacts, or use bathymetry and/or 3D seismic data as a model input. Contributions to this session can include work from any depth or physiographic region, e.g. oceanic plateaus, abyssal hills, mid-ocean ridges, accretionary wedges, and continental margins (from continental shelves to abyss plains). Datasets of any scale, from satellite-predicted depth to ultra high-resolution swath bathymetry, sub-surface imaging and sampling, are anticipated.

This session is organised by the IAG Submarine Geomorphology Working Group.

Contributions are invited on innovative observational, theoretical and modelling studies concerning physical processes in coastal and shelf seas. Processes can include hydrodynamics (e.g., waves, tides, river plumes, currents and Stokes drift, upwelling, eddies, density structures), transport of material (e.g., sediments, contaminants, litter, nutrients), and morphodynamics and sea-bed structure (e.g., evolution of bed forms, banks, Holocene-Antropogene strata or basin shape). Study areas are envisaged between the base of the shelf break and the seaward limit of the surf zone, including tidal basins. However, contributions on processes outside these geographical limits will be considered where they significantly influence processes within these limits. Equally, contributions on climate dynamics, biogeochemistry, and man-made structures will be considered where they significantly influence, or are significantly influenced by, the processes aimed at in this session. Special attention will be given to interactions between physics, biology and biogeochemistry and to global to local scaling of processes, their relative importance, and the representation of these transitions in models.

Oceanographic processes at coastal scales present important differences about deep water oceanography, which result in higher prediction errors for the land-ocean border. In shallow water coastal domains, the bottom topography exerts a strong control on wave/current/turbulence fields and additional factors need to be accounted for. These factors include stratification, land boundary conditions and the interaction with coastal infrastructure. Moreover, the strong non-linear interactions (breaking waves, nearshore circulation), the choice of numerical strategy (nested meshes, finite-elements) or the modulations in restricted domains (suspended sediment clouds, vegetation filtering) may also play a critical role in the predictive quality. Coastal observations are therefore necessary to drive and calibrate numerical models, combining in-situ data and satellite images. The advent of new satellite capabilities (resolution and sensors like for instance those of the Sentinel constellation) and new modelling advances (new couplings, unstructured grids) together with enhanced Coastal Observatories are leading to a qualitative advance of coastal oceanography. The introduction of Artificial Intelligence, Machine Deep Learning and Big Data techniques can speed up these advances and facilitate applications.
These issues become more relevant in a framework of changing climate, since coastal/transitional areas are more strongly impacted by climate (changing domains due to sea-level rise, impulsive river discharges). Because of these reasons, it is timely to discuss recent advances in: a) coastal coupled hydro-morpho-eco modelling; b) aggregation of in-situ/satellite/numerical data from different sources; c) knowledge-based coastal applications; d) ethical constraints to face large uncertainties. Building upon these challenges, we invite presentations on coastal modelling and coupling, local and boundary condition assimilation or operational coastal predictions with/out infrastructure interactions. Contributions exploring the potential and currently open issues of Artificial Intelligence and Big Data techniques for coastal applications are also welcome. These and related coastal topics should conform a fruitful session for discussing applications of coastal science to conventional and nature-based interventions under climate change. Please state if you would be interested in submitting your presentation as a full paper to a peer reviewed special issue in a Q1 journal.

The Mediterranean and Black Seas have recently shown clear signs of climate change, including an increase in sea surface temperature for boths basins, salinization of the intermediate and deep waters and a rise in sea level over the last century for the Mediterranean seas and deoxygenation trends for the Black Sea. These trends stress the vulnerability of these environments given their particularities as semi enclosed densely populated basins.

Urgent social and economic drivers need targeted improvements in weather, climate, water, oceans, and relevant environmental information and services. Risks associated with climate variability and extreme environmental events may create social and economic stress which would require new meteorological, hydrological, oceanographic, and climate services in order to ensure the safety and security of populations and the development of adaptive economic strategies.

This session is devoted to scientific advances in multidisciplinary studies at several spatial and temporal scales in the Mediterranean and Black Seas. We seek for new approaches and methods in physical and biogeochemical observations and models as well as in developments in operational oceanography (e.g. the fusion of observations and modelling products as well as downstream product development).

This session welcomes contributions presenting advances in, and approaches to, the modelling, monitoring, and forecasting of internal waves in stratified estuaries, lakes and the coastal oсean.
Internal solitary waves (ISWs) and large-amplitude internal wave packets are a commonly observed event in oceans and lakes. In the oceans ISWs are mainly generated by the interaction of the barotropic tides with bottom topography. Large amplitude solitary waves are energetic events that generate strong currents. They can also trap fluid with larvae and sediments in the cores of waves and transport it a considerable distance. ISWs can cause hazards to marine engineering and submarine navigation, and significantly impact marine ecosystems and particle transport in the bottom layer of the ocean and stratified lakes. Contributions studying flows due to internal waves, their origin, propagation and influence on the surrounding environment are thus of broad scientific importance.
The scope of the session involves all aspects of ISWs generation, propagation, transformation and the interaction of internal waves with bottom topography and shelf zones, as well as an evaluation of the role of internal waves in sediment resuspension and transport. Breaking of internal-waves also drives turbulent mixing in the ocean interior that is important for climate ocean models. Discussion of parameterizations for internal-wave driven turbulent mixing in global ocean models is also invited.

This session provides a platform for interdisciplinary science addressing the continuum from the river source to the sea. A systems approach is indispensable for science-based solutions to sustainably manage complex River-Sea social-ecological systems. Studies linking environmental and social sciences and crossing geographical borders are particularly invited: from the river source and its catchment through estuaries, deltas and marshlands across the freshwater-marine water transition into the coastal sea, including surface-groundwater interaction. Studies addressing the impacts of climate change and extreme events and the impact of human activities on water and sediment quality and quantity, hydromorphology, biodiversity, ecosystem functioning and services of River-Sea continua are of particular interest.

We need to understand how River-Sea Systems function and to address many open questions. 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 social-ecological 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 balance 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.

The action of a fluid moving over a mobile surface often generates bedforms which in turn influence the flow and how particles are transported. On Earth, bedforms are found in many environments: deserts, rivers, estuaries, continental shelves, deep seas, volcanic regions and glacial environments. Bedforms have also been observed in extra-terrestrial environments, such as on Mars and Venus.

Understanding the links between flow, particle transport, and bedform morphodynamics and stratigraphy is of interest for a wide range of applied and fundamental research. For example, this knowledge is used to manage contemporary environments, such as rivers and coastal seas. Recently, the societal relevance of bedform research has been highlighted, as bedforms are shown to interact with offshore structures. Furthermore, bedform morphology and sedimentology can provide insights into fluid movement across modern and ancient, otherwise unknown, landscapes.

This session aims to highlight many aspects of the complex interaction between flow, sediment transport, stratigraphy and bedforms in terrestrial and planetary environments. The session welcomes contributions from theoretical, field, laboratory and numerical approaches related to bedforms found in aeolian, shallow and deep waters, glacial and planetary environments. The session intends to advance our knowledge of how to decipher information contained in terrestrial and extra-terrestrial bedforms and help foster fruitful discussions on understanding bedform morphodynamics and stratigraphy.

Detailed seabed maps portraying the distribution of geomorphic features, substrates, and habitats are used for a wide range of scientific, maritime industry, and government applications. These maps provide essential information for ocean industry sectors and are used to guide local and regional conservation action. Fundamental to seabed mapping are acoustic remote sensing technologies, including single beam and multibeam echosounders and sidescan, interferometric, and synthetic-aperture sonars. These are deployed on a variety of crewed and robotic surface and underwater platforms. In shallow clear waters, optical sensors including LiDAR, multispectral, and hyperspectral cameras are also increasingly employed from aircraft, drones, and satellites to create maps of the seabed. Innovative data processing, image analysis, and statistical approaches for classification are advancing the field of seabed mapping. These methods are yielding increasingly comprehensive and detailed maps. We welcome submissions that provide insights into the use of advanced technologies, novel processing and analytical approaches, and current and emerging applications in the field of seabed mapping and classification – from shallow coastal waters to the deep seafloor.

Climate induced alterations to key microbial processes, such as net primary production and nitrogen fixation, act alongside changes to the biogeochemical cycling of oxygen and nutrients to affect marine ecosystem structure and function, as well as the ocean carbon cycle. These climate changes operate over a variety of spatiotemporal scales. Today, stratification, warming and acidification are driving global changes in microbial biogeochemistry to affect ocean health. These large-scale, long-term changes are accompanied by the short-term emergence of extremes at the regional scale. And in the past, climate change over glacial-interglacial cycles and even recent multi-decadal variability offer clues to understand how sensitive ocean microbes and biogeochemical cycles are to changes in the climate.
This session seeks submissions, from both observations and modelling efforts, that address the impact of past, present (i.e. historical) and future climate change (including variability) on key microbially-mediated flows. Investigations focussing on net primary production, nitrogen fixation, anaerobic processes in low oxygen zones, and the local to global cycling of nutrients and oxygen are welcome. We also welcome studies that investigate the cascading effects for marine ecosystems to modulate biodiversity and ecosystem services.

Due to the growing pressures on marine resources and the ecosystem services demand, the interest of scientific and politic world is moving to ensure marine ecosystems conservation and environmental sustainable development providing policies to meet the UN 2030 Agenda Goal 14 in order to “Conserve and sustainably use the oceans, seas and marine resources for sustainable development”. To act against the decline of ocean health and to create a framework of stakeholders, the UN proposed the establishment of the “Decade of Ocean Science for Sustainable Development” able to bring regional knowledge and priorities together in an international action plan. Anthropogenic activities could have an impact on the marine environment and affect the ecosystem equilibrium. The marine environment is a dynamic, sensitive and fragile area in which it is advantageous to apply new methodologies and observing methods to increase the quantity and quality of the data. Since ocean dynamics affect the dispersion of pollutants such as chemicals, plastics, noise and invasive species, the ecosystems status should be analyzed through the study of abiotic variables distribution at a proper spatio-temporal scale. To analyze the ocean environmental quality, a large amount of data obtained by global observation systems (e.g. GOOS, EMODNET) is needed, which requires the development of cost-effective technologies for integrated observing systems and to support the study of, e.g., biological variables. The session focuses on marine ecosystems, technological developments for the study of abiotic and biotic factors, with a focus on anthropogenic impacts. Multidisciplinary approaches using data coming from multiple sources are encouraged. Integration of mathematical models, in-situ and remote observations is suggested with the aim to develop methods, technologies and best practices to maintain, restore and monitor biodiversity and to guarantee sustainable use of marine resources. The following topics will be discussed: effects of pollution on biota considering their natural and anthropogenic sources; global change effects on marine ecosystem; new technology development; advanced methods for collection, data processing, and information extraction; benthic and pelagic community dynamics; economic evaluation of natural capital.

Planktonic organisms live in suspension in marine or fresh waters where they have adapted through the slow process of natural evolution (over hundred of thousands of generations) to the harsh turbulent currents of their environment. Therefore, contrary to what the meaning of their name “marine drifter” might let to speculate, their dynamics is potentially different from the one of material bodies passively transported by fluid flows. It is indeed known that these organisms developed many adaptive strategies involving shape and density regulation, swimming activity, aggregation and other mechanisms in order to be sheltered from or to take advantage of turbulent flow features.

Bloom inceptions, thin layers formation, motility, nutrient and light uptakes, specific Lagrangian dynamics, among others are topics involving phytoplankton and turbulence. Jumps, grazing, contact rates, and vertical migration are, among others, topics concerning zooplankton in turbulence. For all planktonic species, adaptive mechanisms in response not only to mechanical, but also chemical and electro-magnetic (such as luminous) cues are topics of great interest.

This interdisciplinary session will welcome works from marine ecologists, oceanographers, fluid-dynamicists, physicists and mathematical modellers. Contributions in the fields of observation, laboratory experimentations, numerical models (such as Computational Fluid Dynamics simulations of non-spherical or motile particles) are welcome. Both phytoplankton and zooplankton will be considered, as well as marine and freshwater studies.

The coastal ocean has been increasingly recognized as a dynamic component of the global carbon budget. This session aims at fostering our understanding of the roles of coastal environments and of exchange processes, both natural or perturbed, along the terrestrial / coastal sea / open ocean continuum in global biogeochemical cycles. During the session recent advancements in the field of coastal and shelf biogeochemistry will be discussed. Contributions focusing on carbon and nutrient and all other element's cycles in coastal, shelf and shelf break environments, both pelagic and sedimentary, are invited.

This session is multidisciplinary and is open to observational, modelling and theoretical studies in order to promote the dialogue. The session will comprise subsections on coastal carbon storage, and on benthic biogeochemical processes.

Ocean-atmosphere flux exchanges of biogeochemically active constituents have significant impacts on global biogeochemistry and climate. Increasing atmospheric deposition of anthropogenically-derived nutrients (e.g., nitrogen, phosphorus, iron) to the ocean influences marine productivity and has associated impacts on oceanic CO2 uptake, and emissions to the atmosphere of climate active species (e.g., nitrous-oxide (N2O), dimethyl-sulfide (DMS), marine organic compounds and halogenated species). Atmospheric inputs of toxic substances (e.g., lead, mercury, cadmium, copper, persistent organic pollutants) into the ocean are also of concern for their impact on ocean ecosystem health. In recent decades the intensive use of plastics has led to significant levels of persistent micro- and nano- plastics being transported into the marine atmosphere and to the ocean, with considerable uncertainty remaining on transport pathways and oceanic impacts. Other influential recent changes include emission reductions for air pollution abatement which have resulted in changes in cloud and aerosol chemical composition, affecting atmospheric acidity, associated chemical processing and impacts via atmospheric deposition on ocean biogeochemistry.
In turn, oceanic emissions of reactive species and greenhouse gases influence atmospheric chemistry and global climate, and induce potentially important chemistry-climate feedbacks. While advances have been made by laboratory, field, and modelling studies over the past decade, we still lack understanding of many of the physical and biogeochemical processes linking atmospheric deposition of chemicals, nutrient availability, marine biological productivity, trace-gas sources and sinks and the biogeochemical cycles governing air-sea fluxes of these climate active species, as well as on the atmosphere-ocean cycle of microplastics and its impact on the environment and climate.
This session will address the above issues on the atmospheric deposition of nutrients and toxic substances to the ocean, the impacts on ocean biogeochemistry, and also the ocean to atmosphere fluxes of climate active species and potential feedbacks to climate. We welcome new findings from measurement programmes (laboratory, in-situ and remote sensing) and atmospheric and oceanic numerical models.
This session is jointly sponsored by GESAMP Working Group 38 on ‘The Atmospheric Input of Chemicals to the Ocean’, the Surface Ocean-Lower Atmosphere Study (SOLAS).

Tides underlie many processes in the ocean, atmosphere and solid Earth, and influence ocean biogeochemistry and ecosystems. They drive ocean mixing, contribute to coastal erosion and sediment transport, and may provide a renewable energy source. Tides influence coastal infrastructure and safe port operations. The severity of storm surge events and coastal flooding is modulated by tides. The relationship between tides and sea ice is also important, not only for sea ice dynamics, but also for transport and mixing processes in the Arctic and Antarctic regions. Interannual variability in the tides may arise from variations in ice extent, changes in ocean stratification or regional climate processes.

Precise knowledge of tides is also necessary for earth observation where the tides are not the main target of study. They play a significant role in determining high-resolution temporal gravity fields from satellite gravimetry as well as sea-level rise estimations from satellite altimetry. Therefore, understanding the evolution of tides from both models and in-situ observations is necessary to understand the implications of tides in current and future climate estimations.

Observations and models of coastal and internal tides continue to develop, as well as their relationships to wind-driven processes and mixing processes. We welcome submissions on observations and models of surface or internal tides in the context of long-term changes in tides, tidal variability, tidal dynamics and the impacts of tides. Submissions are encouraged both from regional and global-scale studies on all aspects of tides.

We invite presentations on ocean surface waves, and wind-generated waves in particular, their dynamics, modelling and applications. This is a large topic of the physical oceanography in its own right, but it is also becoming clear that many large-scale geophysical processes are essentially coupled with the surface waves, and those include climate, weather, tropical cyclones, Marginal Ice Zone and other phenomena in the atmosphere and many issues of the upper-ocean mixing below the interface. This is a rapidly developing area of research and geophysical applications, and contributions on wave-coupled effects in the lower atmosphere and upper ocean are strongly encouraged.

This session welcomes submissions on new insights into the physical processes at the air-sea interface and their role in ocean-atmosphere exchange of heat, gas, momentum, freshwater, and aerosols.
Presentations based on field or satellite observations, numerical models, or theoretical contributions are welcome.

Examples of processes include solar radiation-induced diurnal warming, rain-induced cool and fresh lenses, and processes controlling the formation and properties of the surface microlayer.
Additional focus is on gustiness associated with convection in the atmospheric boundary layer and evaporative cold pools. Further focus is on air-sea interactions in polar regions, in particular related to cold air outbreaks, including the role of sea ice and the effect of leads. Air-sea interaction related to surface temperature and salinity fronts, as well as oceanic meso- and sub-mesoscale dynamics, are also of great interest. Studies considering the variability of biogeochemical properties related to air-sea processes will also be considered.

Oceanographic monitoring and modeling are both widely used to study the pathways and fate of marine pollutants such as hydrocarbons, marine litter (including plastics and microplastics), POPs, HNS, radionuclides, etc. This session focuses on monitoring frameworks, computational tools, experimental results and emerging technologies related to tracing pollutants and their impacts on local, regional and global scales. The coupling with met-oceanographic products from operational oceanography products such as Copernicus Marine Monitoring Environment Service will also be discussed. State-of-the-art observational techniques and protocols, ensemble and multi-model methods, risk assessment algorithms and decision support systems are solicited topics. Integration of modelling and observing systems for both data assimilation and model validation are also very welcome.

We welcome studies based on experimental, observational, and modeling work looking at physical and biogeochemical transformation of pollutants, and impacts on ocean biogeochemistry and ecosystems such as fragmentation, aggregation, biofouling, ingestion but also chemical impacts such as adsorption, transport and desorption of nutrients, metals and microbes. Studies that link effects to broader ecosystem stressors like environmental degradation and climate change are particularly welcome. Monitoring and modeling the oil spill transport under the ice conditions are also appreciated, which is related to the increase in shipping traffic and melting the Polar ice as a consequence of the climate changes.

Key questions of the session are identified as follows: Which factors affect the dispersion of the pollutants in the marine environment? What happens to the contaminants on the ocean’s surface, in the water column and sediments? How do marine pollutants interact with marine habitats? How do they influence marine and maritime resources? How should Integrated Coastal Zone Management (ICZM) protocols be optimized to minimize negative impact on the coastal zone?

Impacts of pollutants, including chemicals, microplastics, light, noise, and thermal pollution, on the marine ecosystems and resilience to pollution events are also important subjects for discussion: What is the behavior of oil, marine litter, heavy metals, and other pollutants in the water column, on various beach sediments, rocks and seabed? e.g., what is the biodegradation rate of oil droplets in the water column and what are the controlling factors? What is the rate of fragmentation, biofouling, and sedimentation of plastics? What are the mechanisms of beaching, seabed deposition, and resuspension of marine pollutants and what are the ways of entering the marine food chains (including human consumption)? What is the impact of light, noise, and thermal pollution on the marine environment and habitats?

Advanced remote sensing capabilities have provided unprecedented opportunities for monitoring and studying the ocean environment as well as improving ocean and climate predictions. Synthesis of remote sensing data with in situ measurements and ocean models have further enhanced the values of oceanic remote sensing measurements. This session provides a forum for interdisciplinary discussions of the latest advances in oceanographic remote sensing and the related applications and to promote collaborations.

We welcome contributions on all aspects of the oceanic remote sensing and the related applications. Topics for this session include but are not limited to: physical oceanography, marine biology and biogeochemistry, biophysical interaction, marine gravity and space geodesy, linkages of the ocean with the atmosphere, cryosphere, and hydrology, new instruments and techniques in ocean remote sensing, new mission concepts, development and evaluation of remote sensing products of the ocean, and improvements of models and forecasts using remote sensing data. Applications of multi-sensor observations to study ocean and climate processes and applications using international (virtual) constellations of satellites are particularly welcome.

NEMO (Nucleus for European Modelling of the Ocean) is a state-of-the-art modelling framework of the ocean that includes components for the ocean dynamics, the sea-ice and the biogeochemistry, so as a nesting package allowing to set up zooms and a versatile data assimilation interface (see https://www.nemo-ocean.eu/).
NEMO is used by a large community in Europe and world-wide (~200 projects, ~100 publications each year) covering a wide range of applications : oceanographic research, operational oceanography, seasonal forecast and climate projections.
NEMO is in particular used in 6 Earth System Models within CMIP6 and in Copernicus Marine Services (CMEMS) model-based products.

This session will provide a forum to properly address the new scientific advances in numerical modelling of the ocean and their implication for NEMO developments associated with:
• Ocean dynamics at large to coastal scales, up to 1km resolution ;
• Ocean biogeochemistry
• Sea-ice
• New numerical schemes associated to energy conservation constraints
• High performance computing challenges and techniques

The session will cover both research and operationnal activities contributing to new analysis, ideas and developments of ocean numerical models.
Presentations of results based on new NEMO functionalities and new NEMO model configurations are welcome.

Since its inception, data assimilation has proven to be enormously useful in the most varied fields throughout the Earth Sciences. It is certainly essential in meteorology, where the short-range forecasts would otherwise be almost impossible. In oceanography, its development has been slower, partly due to the smaller number of continuous and stable observations, and partly due to the fewer studies that show the importance of ocean forecasts for societal benefit. However, recently, these techniques are used more and more widely, both in operational oceanography and to produce climate reconstructions. Although the techniques are similar to those used in the atmospheric field, they have to deal with particularities due to the different environment, where the boundary conditions, open and closed, have greater importance, and the sparsity of observations poses unique challenges.
In this session, we welcome contributions describing data assimilation techniques, both methodological and case studies, in the oceanographic field. We welcome presentations of new techniques or new types of observations that cover every aspect of data assimilation, including varied applications of data assimilation, both in coastal seas and the open ocean.

The Copernicus Marine Service (CMEMS) provides regular and systematic reference information on the physical (including sea-ice and wind waves) and biogeochemical states of the global ocean and European regional seas. This capacity encompasses the description of the current ocean state (analysis and near-real time observations), the prediction of the ocean state a few days ahead (forecast), and the provision of consistent retrospective data records for recent decades (reanalyses and reprocessed observations). CMEMS provides a sustainable response to private and public user needs, for academic, operational and private-sector activities and to support policies. The Copernicus Marine Service has started a new 7-yr phase covering 2021-2027 (CMEMS2).

The session focuses on the main CMEMS activities on ocean modelling and coupling with other components of the climate system; data assimilation; processing of observations, impact and design of in-situ and satellite observing systems, data science; verification, validation and uncertainty estimates of CMEMS products; monitoring and long-term assessment of the ocean physical and biogeochemical states. Presentations dealing with the use and impact of CMEMS products for downstream applications, including support to policies and directives, are also welcome.

The session will also address research activities that are required to maintain a state-of-the-art and user responsive CMEMS and to prepare CMEMS long-term evolutions: pan-European coastal zone monitoring, coupling with coastal systems and rivers, marine biology including higher trophic level modelling, Arctic ocean monitoring and forecasting and uptake of future Sentinel missions, air/sea CO2 fluxes and carbon uptake, long-term regional ocean projections both for physics and biogeochemistry, digital oceans, big data and data science (AI, machine learning, etc).

Presentations are not limited to research teams directly involved in the Copernicus Marine Service and participation from external teams is strongly encouraged (e.g. from H2020 projects relevant to CMEMS and downstream applications).

The session gathers geoscientific aspects such as dynamics, reactions, and environmental/health consequences of radioactive materials that are massively released accidentally (e.g., Chernobyl and Fukushima nuclear power plant accidents, wide fires, etc.) and by other human activities (e.g., nuclear tests).

The radioactive materials are known as polluting materials that are hazardous for human society, but are also ideal markers in understanding dynamics and physical/chemical/biological reactions chains in the environment. Thus, the radioactive contamination problem is multi-disciplinary. In fact, this topic involves regional and global transport and local reactions of radioactive materials through atmosphere, soil and water system, ocean, and organic and ecosystem, and its relations with human and non-human biota. The topic also involves hazard prediction and nowcast technology.

By combining 35 years (> halftime of Cesium 137) monitoring data after the Chernobyl Accident in 1986, 10 years dense measurement data by the most advanced instrumentation after the Fukushima Accident in 2011, and other events, we can improve our knowledgebase on the environmental behavior of radioactive materials and its environmental/biological impact. This should lead to improved monitoring systems in the future including emergency response systems, acute sampling/measurement methodology, and remediation schemes for any future nuclear accidents.


The following specific topics have traditionally been discussed:
(a) Atmospheric Science (emissions, transport, deposition, pollution);
(b) Hydrology (transport in surface and ground water system, soil-water interactions);
(c) Oceanology (transport, bio-system interaction);
(d) Soil System (transport, chemical interaction, transfer to organic system);
(e) Forestry;
(f) Natural Hazards (warning systems, health risk assessments, geophysical variability);
(g) Measurement Techniques (instrumentation, multipoint data measurements);
(h) Ecosystems (migration/decay of radionuclides).

The session consists of updated observations, new theoretical developments including simulations, and improved methods or tools which could improve observation and prediction capabilities during eventual future nuclear emergencies. New evaluations of existing tools, past nuclear contamination events and other data sets also welcome.

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

The main aim of the session is to initiate discussion of the multitude of processes active under strong winds across the narrow specializations as a step towards creating an integrated picture. Theoretical, numerical, experimental and observational works are welcomed.

In his seminal work "Weather Prediction by Numerical Process" in 1922, Lewis Fry Richardson proposed his famous cascade picture qualitatively, for a turbulent flow where the energy is transferred from large scale structures to small scale ones, until reaching viscosity scales where it is converted to heat. This picture now has been widely adopted to describe different type of turbulent phenomena, for not only the classical hydrodynamic turbulence, but also, not limited to, the movement of atmosphere and oceans.

After 100 years of developments, the concept of cascades has been extended significantly. Now, it describes mainly the nonlinear interactions crossing a large range of scales where scale invariants might emerge spontaneously. More precisely, balances between the external forcing and the dissipation are expected for a turbulent system. However, due to the complexity of atmospheric or oceanic systems, such as earth rotation, stratification, large aspect ratio, mesoscale eddies, ocean current, tidal, waves, etc., the exact balance is still unknown. We still lack an efficient methodology to diagnose the scale-to-scale energy or other physical quantities fluxes to characterize the cascade quantitatively, e.g., strength, direction, etc.

With the increasing capability of remote sensing, computational fluid dynamics, field observation, etc., we have accumulated a large amount of field data. It is now a suitable time to celebrate the 100th Anniversary of Richardson's idea of cascades in the geosciences, and to understand it quantitatively.
This interdisciplinary session welcomes theoretical, methodological, laboratory, data analysis works that aim to characterize the cascade in atmosphere and oceans and other fields.

This session invites innovative Earth system and climate studies based on geodetic measuring techniques. Modern geodetic observing systems document a wide range of changes in the Earth’s solid and fluid layers at very diverging spatial and temporal scales related to processes as, e.g., glacial isostatic adjustment, the terrestrial water cycle, ocean dynamics and ice-mass balance. Different time spans of observations need to be cross-compared and combined to resolve a wide spectrum of climate-related signals. Geodetic observables are also often compared with geophysical models, which helps to explain observations, evaluate simulations, and finally merge measurements and numerical models via data assimilation.
We appreciate contributions utilizing geodetic data from diverse geodetic satellites including altimetry, gravimetry (CHAMP, GRACE, GOCE and GRACE-FO), navigation satellite systems (GNSS and DORIS) or remote sensing techniques that are based on both passive (i.e., optical and hyperspectral) and active (i.e., SAR) instruments. We welcome studies that cover a wide variety of applications of geodetic measurements and their combination to observe and model Earth system signals in hydrological, ocean, atmospheric, climate and cryospheric sciences. Any new approaches helping to separate and interpret the variety of geophysical signals are equally appreciated. Contributions working towards any of the goals of the Inter-Commission Committee on "Geodesy for Climate Research" (ICCC) of the International Association of Geodesy (IAG) are also welcomed in this session.
With author consent, highlights from this session will be tweeted with a dedicated hashtag during the conference in order to increase the impact of the session.

Tsunamis can produce catastrophic damage on vulnerable coastlines, essentially following major earthquakes, landslides, extreme volcanic activity or atmospheric disturbances. After the disastrous tsunamis in 2004 and 2011, tsunami science has been continuously growing and expanding its scope to new fields of research in various domains, and also to regions where the tsunami hazard was previously underestimated.

The spectrum of topics addressed by tsunami science nowadays ranges from the “classical” themes, such as analytical and numerical modelling of different generation mechanisms (ranging from large subduction earthquakes to local earthquakes generated in tectonically complex environments, from subaerial/submarine landslides to volcanic eruptions and atmospheric disturbances), propagation and run-up, hazard-vulnerability-risk assessment, especially with probabilistic approaches able to quantify uncertainties, early warning and monitoring, to more “applied” themes such as the societal and economic impact of moderate-to-large events on coastal local and nation-wide communities, as well as the present and future challenges connected to the global climate change.

This session, co-organized with OS4, SM4, GMPV9, GM and AS, welcomes multidisciplinary as well as focused contributions covering any of the aspects mentioned above, encompassing field data, geophysical models, regional and local hazard-vulnerability-risk studies, observation databases, numerical and experimental modeling, real time networks, operational tools and procedures towards a most efficient warning, with the general scope of improving our understanding of the tsunami phenomenon, per se and in the context of the global change, and our capacity to build safer and more resilient communities.

Recently, there have been significant breakthroughs in the use of fiber-optic sensing techniques to interrogate cables at high precision both on land and at sea as well as in boreholes and at the surface. Laser reflectometry using both fit-to-purpose and commercial fiber-optic cables have successfully detected a variety of signals including microseism, local and teleseismic earthquakes, volcanic events, ocean dynamics, etc. Other laser-based techniques can be used to monitor distributed strain, temperature, and even chemicals at a scale and to an extent previously unattainable with conventional geophysical methods.

We welcome any contributions to recent development in the fields of applications, instrumentation, and theoretical advances for geophysics with fiber-optic sensing techniques. These may include - but are not limited to - application of fiber-optic cables or sensors in seismology, geodesy, geophysics, natural hazards, oceanography, urban environment, geothermal application, etc. with an emphasis on laboratory studies, large-scale field tests, and modeling. We also encourage contributions on data analysis techniques, machine learning, data management, instruments performances and comparisons as well as new experimental field studies.

Satellite altimetry provides the possibility to observe key parts of the hydrosphere, namely the ocean, ice, and continental surface water from space. Since the launch of Topex/Poseidon in 1992, the applications of altimetry have expanded from the open oceans to coastal zones, inland water, land, and sea ice. Today, seven missions are in orbit, providing dense and near-global observations of surface elevation and several other parameters. Satellite altimetry has become an integral part of the global observation of the Earth‘s system and changes therein.

In recent years, new satellite altimetry missions have been launched carrying new instruments; the CryoSat-2/Sentinel-3 missions equipped with a Delay/Doppler altimeter, the Saral AltiKa mission carrying the first Ka-band altimeter, and 2018 launched six beam photon-counting laser altimeter onboard NASAs ICESat-2. Further, new orbits with high inclination and long-repeat time are used for CryoSat-2 and ICESat-2.


Fully exploiting this unprecedented availability of observables will enable new applications and results but also require novel and adapted methods of data analysis.
Across the different applications for satellite altimetry, the data analysis and underlying methods are similar and a knowledge exchange between the disciplines has been proofed to be fruitful.
In this multidisciplinary altimetry session, we therefore invite contributions which discuss new methodology and applications for satellite altimetry in the fields of geodesy, hydrology, cryosphere, oceanography, and climatology.
Topics of such studies could for example be (but not limited to); creation of robust and consistent time series across sensors, validation experiments, combination of radar and laser altimetry for e.g. remote sensing of snow, classification of waveforms, application of data in a geodetic orbit, retracking, or combination with other remote sensing data sets.

The International Monitoring System (IMS) of the Comprehensive Nuclear-Test-Ban Treaty (CTBT) senses the solid Earth, the oceans and the atmosphere with a global network of seismic, infrasound, and hydroacoustic sensors as well as detectors for atmospheric radioactivity. The primary purpose of the IMS data is for nuclear explosion monitoring regarding all aspects of detecting, locating and characterizing nuclear explosions and their radioactivity releases. On-site verification technologies apply similar methods on smaller scales as well as geophysical methods such as ground penetrating radar and geomagnetic surveying with the goal of identifying evidence for a nuclear explosion close to ground zero. Papers in this session address advances in the sensor technologies, new and historic data, data collection, data processing and analysis methods and algorithms, uncertainty analysis, machine learning and data mining, experiments and simulations including atmospheric transport modelling. This session also welcomes papers on applications of the IMS and OSI instrumentation data. This covers the use of IMS data for disaster risk reduction such as tsunami early warning, earthquake hazard assessment, volcano ash plume warning, radiological emergencies and climate change related monitoring. The scientific applications of IMS data establish another large range of topics, including acoustic wave propagation in the Earth crust, stratospheric wind fields and gravity waves, global atmospheric circulation patterns, deep ocean temperature profiles and whale migration. The use of IMS data for such purposes returns a benefit with regard to calibration, data analysis methods and performance of the primary mission of monitoring for nuclear explosions.

Through a wealth of geospatial data, growing computational power, and demonstrated success of application across many fields, artificial intelligence (in particular, machine learning) promises to advance our understanding of natural hazards and our ability to predict and respond to natural disasters. The ITU/WMO/UNEP Focus Group AI for Natural Disaster Management (FG-AI4NDM) is building a community of experts and stakeholders to identify best practices in the use of AI for data processing, improved modeling across spatiotemporal scales, and providing effective communication. This multidisciplinary FG-AI4NDM-session invites contributions addressing challenges related to floods, landslides, earthquakes, volcanic eruptions, tsunamis, among others, as well as multi-hazard. It also welcomes presentations on novel AI methods (including advances in automated annotation, explainability, etc.), which are hazard agnostic.

Citizen science (the involvement of the public in scientific processes) is gaining momentum across multiple disciplines, increasing multi-scale data production on Earth Sciences that is extending the frontiers of knowledge. Successful participatory science enterprises and citizen observatories can potentially be scaled-up in order to contribute to larger policy strategies and actions (e.g. the European Earth Observation monitoring systems), for example to be integrated in GEOSS and Copernicus. Making credible contributions to science can empower citizens to actively participate as citizen stewards in decision making, helping to bridge scientific disciplines and promote vibrant, liveable and sustainable environments for inhabitants across rural and urban localities.
Often, citizen science is seen in the context of Open Science, which is a broad movement embracing Open Data, Open Technology, Open Access, Open Educational Resources, Open Source, Open Methodology, and Open Peer Review. Before 2003, the term Open Access was related only to free access to peer-reviewed literature (e.g., Budapest Open Access Initiative, 2002). In 2003 and during the “Berlin Declaration on Open Access to Knowledge in the Sciences and Humanities”, the definition was considered to have a wider scope that includes raw research data, metadata, source materials, and scholarly multimedia material. Increasingly, access to research data has become a core issue in the advance of science. Both open science and citizen science pose great challenges for researchers to facilitate effective participatory science, yet they are of critical importance to modern research and decision-makers.

We want to ask and find answers to the following questions:
Which approaches and tools can be used in Earth and planetary observation?
What are the biggest challenges in bridging between scientific disciplines and how to overcome them?
What kind of participatory citizen scientist involvement (e.g. how are citizen scientists involved in research, which kind of groups are involved) and open science strategies exist?
How to ensure transparency in project results and analyses?
What kind of critical perspectives on the limitations, challenges, and ethical considerations exist?
How can citizen science and open science approaches and initiatives be supported on different levels (e.g. institutional, organizational, national)?

Unsupervised, supervised, semi-supervised as well as reinforcement learning are now increasingly used to address Earth system related challenges.
Machine learning could help extract information from numerous Earth System data, such as in-situ and satellite observations, as well as improve model fidelity through novel parameterisations or speed-ups. This session invites submissions spanning modelling and observational approaches towards providing an overview of the state-of-the-art of application of these novel methods for predicting and monitoring our earth system. This includes (but it is not restricted to):
- the use of machine learning to improve forecast skill
- generate significant speedups
- design new parameterization schemes
- emulate numerical models.

Please consider submitting abstracts focussed on ML applied to observations and modelling of climate processes to the companion "ML for Climate Science" session.

The 2021-2022 Hunga Tonga-Hunga Ha'apai eruption in Tonga was among the largest of recent decades. The event was notable for its high intensity, generating a convective column that rapidly ascended well into the stratosphere; for the atmospheric pressure wave generated by the explosion, which was detected globally; and for generating a tsunami that was observable across Pacific Ocean shorelines. Following a series of preceding seismic and explosive events since December 2021, the sustained phase of the eruption on 15th January was relatively short lived, but the associated pressure wave and tsunami impacts were the most far-reaching since the eruption of Krakatau volcano in 1883. Tsunamis were recorded both locally and in the far-field, but their mechanism(s) remains uncertain; in the near field being from either (or both of) the collapsing eruption column or a phreatomagmatic explosion as the erupting mass mixed with sea water. In the far-field the tsunamis are possibly best explained by the massive atmospheric pressure wave, that is the first instrumentally recorded eruption-generated event of its type, which affected the entire global atmosphere and ionosphere, causing the observed infrasound waves and unusual long-period seismic resonances.
This interdisciplinary late-breaking session welcomes contributions from all disciplines involved in local and global observations of this eruption and its effects, including remote sensing observations and modeling as well as hazard assessment and estimation of damage and long-term consequences.

Meet editors of internationally renowned journals in geo- and biogeoscience and gain exclusive insights into the publishing process. After a short introduction into some basics, we will start exploring various facets of academic publishing with short talks given by the editors on

- What are the duties and roles of editors, authors and reviewers?
- How to choose a suitable journal for your manuscript and what is important for early career authors?
- How can early career scientists get involved in successful peer-reviewing?
- What is important for appropriate peer-reviewing?
- What are ethical aspects and responsibilities of publishing?

Together with the audience and the editors, we will have an open discussion of the key steps and factors shaping the publication process of a manuscript. This short course aims to provide early career scientists across several EGU divisions (e.g. AS, BG, CL, GM, NH, SSP and SSS) the opportunity of using first hand answers of experienced editors of international journals to successfully publish their manuscripts and get aware of the potentials and pitfalls in academic publishing.

On 9 August 2021, the Intergovernmental Panel on Climate Change (IPCC) released the first volume of its 6th Assessment Report (AR6). The Working Group I contribution to the Report (Climate Change 2021: The Physical Science Basis) synthesises over 14,000 publications and represents the most comprehensive and up-to-date assessment of the climate system and climate change. Crucially, the Report highlights the unprecedented and potentially irreversible influence of anthropogenic climate forcing, and for the first time, explicitly states that human influence on the climate system is unequivocal.

This short course will be a panel discussion where authors and contributors of Working Group I unpack how the IPCC 6th Assessment Report (AR6) is produced, provide personal behind-the-scenes insight on its development, and discuss its global impact, including how it is used to inform policy. Authors of the report will share their experiences of working on the report before and through the COVID pandemic. Panelists will also emphasise various ways in which scientists of all career stages can contribute to the IPCC process. Ample time will be allocated for open discussion for the audience to ask related questions to the panelists.

For more information about the AR6 please visit the IPCC website: https://www.ipcc.ch/.

We have developed an open source software package in python for ground-based GNSS reflections – gnssrefl (https://github.com/kristinemlarson/gnssrefl). This new software supports geoscientists wishing to measure in situ snow accumulation, permafrost melt, firn density, tides, and lake/river levels. We have developed videos (hosted on youtube) to help new users understand both the basic concepts of GNSS reflections and how to install and run the gnssrefl code. More than a dozen use cases are available online; Jupyter Notebooks have been developed as well. We envision the EGU tutorial session to be hands-on and interactive, with a focus on demonstrating the gnssrefl software and online tools (https://gnss-reflections.org), examining and discussing environmental results derived from GNSS data taken from public archives, and analyzing new datasets suggested by the students.