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 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 projects have been focused on the Atlantic circulation changes, for instance OVIDE, RACE, OSNAP, and ACSIS. 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.

Please note that while we hope to hold a session in the traditional format, we anticipate that some part or all of the session may be held online.

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

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 with a focus on emerging cryospheric, oceanic and biogeochemical processes and their implications are particularly welcome.
The session promotes results from current Arctic programmes and discussions on future plans for Arctic Ocean modelling and measurement strategies, and encourages submissions on the first results from CMIP6 and the recently completed 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.

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, as well as its variability on (intra)seasonal, interannual, and decadal timescales. They also make the basin and its surrounding regions, which are home to a third of the global population, particularly vulnerable to anthropogenic climate change: robust trends in heat transport and freshwater fluxes have been observed in recent decades in the Indian Ocean and Maritime Continent region and 2019 marked one of the largest Indian Ocean Dipole events on record. 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 and projected changes in Indian Ocean physical and biogeochemical properties and their impacts on ecological processes, 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 view of the large 2019 event, contributions on the Indian Ocean Dipole mechanisms and climate impacts, with a particular focus on extreme events, are particularly sought. 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), and the Year of the Maritime Continent (YMC) programs.

The Southern Ocean is a key region for the vertical and lateral exchanges of heat, carbon, and nutrients, with significant past and potential future impacts on the global climate system. However, the role of the Southern Ocean as a sink of anthropogenic carbon and heat, and as a source of natural carbon remains uncertain. Indeed, observations of many aspects of this system are still sparse and the ability to model the complex dynamics governing the air-sea exchange, export and storage of heat and carbon is limited, resulting in large climate projection uncertainties.

To address these knowledge gaps the Southern Ocean has been the subject of recent large-scale observational, theoretical and modelling investigations by several national and international programmes, including SOCCOM, the UK ORCHESTRA and RoSES, and the H2020 programme SO-CHIC, complimented by the IODP and other drilling programmes. These and other large scale efforts such as the CMIP6 simulations have provided insight into the processes governing the Southern Ocean heat and carbon exchanges, their spatial patterns and trends on subannual, multi-decadal and millennial timescales, as well as their potential future modifications under a changing climate.

This session welcomes contributions dealing with the physical, biogeochemical and ecological processes driving the air-sea exchange, export, and storage of heat and carbon in the Southern Ocean under past, present, and future climates. These include (but are not limited to) interior ocean mixing, water mass transformation and transport pathways, the cycling of carbon and nutrients, as well as ocean-ice-atmosphere interactions and fluxes. The session will also discuss the wider implications of changing Southern Ocean heat and carbon exchanges for the lower latitudes and for the global climate.

In recent years 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? What controls the inflow of warm water into ice shelf cavities and what is the impact of enhanced meltwater outflow? What role do ice processes play in nutrient upwelling on the shelf? 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.

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 feedback (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).

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.

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.

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.

Feedbacks between the ice sheets, oceans, atmosphere and global climate remain uncertain under past, present and future climates. In particular, ice core and marine sediment records suggest that some parts of the Antarctic Ice Sheet (AIS) have remained stable during past interglacials, while the Northern Hemisphere ice sheets and other parts of the AIS may have become unstable, potentially leading to rapid ice loss and sea level rise. Tipping points in modern ice sheets and polar seas need evaluating so that the risk of rapid, potentially irreversible sea level rise under ongoing climate warming can be assessed with more confidence. In addition, the influences of increasing melt water fluxes on ice-ocean interactions and on global climate need to be understood in more detail. In this session we are particularly interested in (1) the likely dynamic stability or instability of ice sheets and polar seas in the near future, based on evidence from their past or present behaviour, and (2) feedbacks between rapid ice loss, ocean circulation, sea ice and the atmosphere. We welcome contributions addressing these issues based on model simulations, modern observations, paleo evidence and theory.

The 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 (as 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.

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 understanding ENSO and its tropical basins interactions in models of a range of complexity are especially welcomed, including analysis of CMIP model intercomparisons.

In this session, we invite presentations that investigate CMIP6 (or other, similarly co-ordinated) simulations.

Analysis of the Sixth Coupled Model Intercomparison Project (CMIP6) is now well underway. Here, we focus on analyses of coordinated simulations undertaken through, or parallel to, the CMIP protocol, with a particular focus on historical simulations and future projections. We are particularly interested in analyses that involve a role for the North Atlantic region, either in evaluating/describing simulated/projected variability or in the North Atlantic’s remote effect on other regions. We are interested in (multi)model evaluation, mechanisms of variability, as well as impact analysis. Multimodel analyses are especially welcome as are critical comparisons between models and observations.

We invite presentations that investigate CMIP (or similarly co-ordinated) simulations on topics including, but not limited to, the following:

-o- The historical and future evolution of the Atlantic Meridional Overturning Circulation (AMOC)
-o- Projected changes in the strength and location of the jet stream
-o- Atlantic Multidecadal Variability (AMV), including future changes and the role of internally/externally forced variability
-o- Projections or mechanisms of changes in hurricane activity
-o- The drivers and impacts of Arctic ice melt
-o- The hydrological cycle and freshening of the North Atlantic, including “hosing” simulations
-o- Teleconnections between the North Atlantic and remote regions including over land

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.

Coastal regions constitute an extremely dynamic portion of the ocean, and a hotspot for production, recycling and biodiversity. They are located at the external boundaries of the wide open ocean basin, with which they exchange significant amounts of physical and biogeochemical tracers, determining large-scale ocean equilibria.

In this session, we focus on the processes that drive the lateral coupling between the coastal and the open waters and on the large-scale impact of these fluxes. We are interested in studies that focus on the physical drivers of this lateral exchange and on their spatial and temporal variability, as well as on the relative role of small scale and large scale transport. Coastal-open ocean transport is mediated by coastal filaments, eddies, Ekman transport, and other processes advecting carbon, dissolved nutrients, and organisms. We welcome projects that explore how cross-shore exchange fluxes impact the nutrient and carbon cycles on the large scale, and projects that explore the role of this lateral transport in the ecosystem connectivity (e.g., larval transport). We are interested in comparing how the key drivers of the coastal-open ocean exchange vary at the boundary of different types of coastal settings. We welcome studies that identify key hotspots and pathways of lateral connectivity, both in a Eulerian and in a Lagrangian perspective. We invite both modeling and observational studies that address either short-term or long-term variations in coastal-open ocean connectivity.

Our session aims at highlighting the global significance of coastal regions, connecting two traditionally distinct research communities: the one that focuses on coastal and shelf ocean processes, and the one that focuses on the open ocean.

Oceanographic processes at coastal scales present a number of important differences with respect to deep water oceanography, which result in higher prediction errors. In shallow water coastal domains, the bottom topography exerts a strong control on the resulting wave/current fields and other factors need to be accounted for (stratification and mixing effects or land boundary condition). Moreover, the coupling between wind, waves, currents and sediments at limited scales, or even the choice of numerical strategy (nested meshes, finite-elements, etc.) may also play a critical role in the quality of the predictions. Coastal observations are therefore necessary to drive 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 (coupling, unstructured grids and boundary conditions) together with enhanced coastal observatories should lead to a qualitative advance of coastal oceanography. The introduction of Artificial Intelligence, Machine Deep Learning and Big Data techniques can speed up the required advances and facilitate applications.
These issues are even more relevant in a framework of changing climate, since coastal and transitional areas are strongly impacted by climate. Because of these reasons, it is timely to discuss recent advances in fields such as: coupled ocean-atmosphere-sediment modelling; hydrological, biogeochemical and geomorphological variability of coastal regions; aggregation of in-situ/satellite/numerical Big Data; criteria for optimising integrated coastal predictions and observatories. Building upon these challenges, we invite for this session presentations on satellite/in-situ measurements, coastal assimilation, metocean-riverine coupling, water/sediment/nutrient fluxes through coastal systems, operational predictions and observations and coastal error limits and uncertainties. These topics, emphasizing coastal variability (hydrodynamics, morphodynamics and bio-geochemical processes) and their interactions with coastal infrastructure/activities should conform a fruitful session for coastal ocean science, where we intend to organise a special collection of the best presentations for an EGU journal.

The session would like to overview recent developments and understanding, by observations and modelling, of the Southern European Seas (SES) general circulation, physical processes, biogeochemical interactions and their ecosystems. Themes of particular interest are: - Interaction of scales and processes in the SES: hydrodynamic and ecosystem interactions at multiple temporal and spatial scales (down to submesoscale), coastal processes and shelf-to-open sea interactions, straits dynamics, ocean response to atmospheric forcing, impact of environmental conditions on ecosystem functions from local to regional scales; - Assessing, understanding and predicting the potential impact of climate change in the SES: long term trends, occurrence of extreme events, development of downscaled models at basin and regional scales, novel approaches to model marine ecosystems, ecosystem functions and biodiversity; - Integrated Observing System in the SES: development of new sensors, scale of interests, development of advanced methodologies for upscaling local information, new satellite products, processes that need to be monitored, identification of data gaps (eg. observing system experiments); - Operational Oceanographic products in the SES: merging of observations and modelling products, downstream products development in the framework of the Mediterranean Sea Oceanography Network for GOOS (MONGOOS). Production and use of services for continuously advance in the scientific understanding and technological development in support to sustainable Blue Growth, SDGs implementation.
- Science-based Integrated management of the SES: support to Marine Spatial Planning and deployment of Marine Protected Areas , scenario studies, mapping of anthropogenic pressures, habitat and ecosystem services, potential support for nature-based solutions and/or sustainable exploitation of marine resource.

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

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

It has been shown that regional climate change interacts with many other man-made perturbations in both natural and anthropogenic coastal environments. Regional climate change is one of multiple drivers, which have a continuing impact on terrestrial, aquatic and socio-economic (resp. human) environments. These drivers interact with regional climate change in ways, which are not completely understood. Recent assessments all over the world have partly addressed this issue (e.g. Assessment of Climate Change for the Baltic Sea region, BACC (2008, 2015); North Sea Climate Change Assessment, NOSCCA (2011); Canada’s Changing Climate Report, CCCR (2019)).
This session invites contributions, which focus on the connections and interrelations between climate change and other drivers of environmental change, be it natural or human-induced, in different regional seas and coastal regions. Observation and modelling studies are welcome, which describe processes and interrelations with climate change in the atmosphere, in marine and freshwater ecosystems and biogeochemistry, coastal and terrestrial ecosystems as well as human systems. In particular, studies on socio-economic factors like aerosols, land cover, fisheries, agriculture and forestry, urban areas, coastal management, offshore energy, air quality and recreation, and their relation to climate change, are welcome.
The aim of this session is to provide an overview over the current state of knowledge of this complicated interplay of different factors, in different regional seas and coastal regions all over the world.

The net amount of CO2 that is taken up and stored by the ocean is a major driver of the rate of climate change but also affects biogeochemical stressors such as ocean acidification. Alongside the gradual increase in the ocean’s anthropogenic carbon inventory, the uptake, storage, and transformation of carbon display a large degree of spatial and temporal variability. In this session, we wish to shine a light on such trends and variability in ocean carbon dynamics, focussing on underlying processes and the consequences for marine ecosystems in the recent past, present, and future.

We are specifically interested in temporal changes in the fluxes and inventories of natural and anthropogenic inorganic carbon, as well as other marine carbonate system parameters, such as alkalinity, pCO2, and pH. We welcome contributions with a focus on the open or coastal ocean, surface, and/or ocean interior, based on observations, models, or theory and with a global or regional focus. Observational and multi-model constraints on marine carbon dynamics are particularly welcome, as are studies based on GLODAP or SOCAT data and insights from the recent Coupled Model Intercomparison Project Phase 6 (CMIP6) simulations.

To keep global warming below 2°C, rapid emission reductions will likely be supported with negative emission technologies (NETs) that pull CO2 out of the atmosphere and store it in other reservoirs. The ocean reservoir naturally takes up about 25% of anthropogenic CO2 emissions. Its storage capacity can potentially be increased through various ocean NETs including enhanced weathering, ocean fertilization, artificial upwelling, or ocean afforestation.
Removing carbon from seawater through engineered approaches or by harvesting of marine biomass to make biofuels or biochar, can also potentially reduce atmospheric CO2 as long as the extracted carbon is ultimately stored in another reservoir at the end of the process. These strategies have yet to be developed to scale, and their feasibility, costs, upscaling potential, environmental side-effects, and social and political implications are still largely unknown.
The goal of this session is to bring together scientists from various backgrounds related to ocean NETs to assess and discuss their feasibility, costs, as well as potential co-benefits and environmental risks. We explicitly also welcome experts working on the interface of ocean- and land-based NETs as well as, on social issues, ocean management-related questions, and legal aspects.

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.

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.

Humic substances are in the focus of many specialists representing different disciplines, including chemists and scientists from soil, coal, freshwater, and marine sciences. The mutual interaction of humic substances with heavy metals, pesticides, PAHs, micro- and nano-plastics, antibiotics and other xenobiotics is one of the most important aspects of their accumulation and translocation in contaminated and uncontaminated environmental compartments. These general considerations render this interdisciplinary topic extremely important for environmental pollution. Fate and activity of xenobiotics depend on their interaction with organic matter and specific humic fractions that may influence their bioavailability in soil due to various interactions with these substances. At the same time, they may affect the properties of humic substances, playing a crucial role in several processes determining quality of the terrestrial and aquatic systems. The session will cover various aspects of mutual interaction between humic substances and a broad spectra of xenobiotics and will provide deeper insights and understanding of their behavior mechanisms in relation to humic substances, that occurs naturally in the environment.

Reliable information on past environmental and climatic conditions is crucial for understanding the evolution of life and the Earth System as a whole. Skeletal components of marine or aquatic organisms are among the most important and widely-used natural archives capturing information about the environment and fluid chemistry during precipitation in the form of geochemical signatures and/or specific mineralogies or micromorphologies. Over the past decades, a refined understanding of (bio)mineralisation, together with the development of new isotopic and elemental proxies (e.g. clumped isotopes Δ47, boron isotopes δ11B, or elemental ratios such as Li/Mg), has led to numerous breakthroughs in palaeoclimate research (e.g. on the evolution of seawater chemistry, causes and consequences of mass extinctions, or greenhouse vs. icehouse climate sensitivities). Simultaneously, geochemical, petrographic and crystallographic approaches have brought novel insights into (bio)mineral formation processes and alteration pathways of a variety of organisms. Critically, however, our knowledge of the incorporation of elements into the crystal lattice, and the quality and reliability of extracted climatic and environmental records, depends on careful proxy calibrations, and evaluation of secondary controls such as kinetic or vital effects and diagenetic influences.

This session seeks contributions on geochemical proxy development, including but not limited to new proxies, calibrations, modelling frameworks, and analytical or methodological advances. We invite experimental and observational studies dealing with biogenic but also inorganic mineral precipitation, transformation and alteration, including interface geochemistry, geomicrobiology or new perspectives on biomineralisation from culturing of calcifying organisms. We also welcome examples on how mechanistic understanding of marine or terrestrial carbonates and/or application of novel approaches results in an improved understanding of the global carbon(ate) cycle and Earth history. The aim of this session is to synthesize recent advances in geochemistry and (bio)mineralisation to further palaeo-proxy development and application that will result in a comprehensive understanding of past global changes.

Biological and ecological experimental studies in laboratory and nature, and their applications to the paleo- and future understanding of marine environments

In order to discuss Earth marine realms and answer questions about biotic evolution and ecosystem functioning in the Past, Present and Future, scientists try to take various laboratory- or natural-based experimental approaches. This includes experiments controlling environmental variables, experiments with stable or radioactive isotopic biomarkers, breeding experiments, genetic analyses (e.g. ancient DNA), or so-called natural laboratories (e.g. the Lessepsian invasion via the Suez Canal or natural CO2 vents functioning as ocean acidification analogues). Altogether, they unriddle faunal and ecosystem functional responses to changing connectivity patterns, habitat change or global change threats. These experimental approaches are effective to make clear how biotic evolution takes place in nature, how ecosystems also act as functional labs and how Earth systems have moved and can move dynamically. They enable us to make more robust projections into the future or decipher past ecosystem trajectories with potential analogues to future change. In this session we welcome contributions that use experimental approaches in this context, but also discussing biogeochemical proxies that fix information of past environmental change during biomineralization in calcareous or siliceous tests.

Climate change is causing abrupt changes in greenhouse gas (GHG) cycles, either by altering biogenic fluxes, or changes in anthropogenic emissions as witnessed during the Covid-19 pandemic. Hence, we need to integrate all feedbacks taking place between the climate system and the GHG cycles. While the Covid-19 shutdown led to 17% reduction in daily global CO2 emissions, large forest-fires erupted across the Americas, Australia and the Arctic circle in 2019 and 2020, releasing greenhouse gases and destroyed forests which take up CO2. Global warming leads to early, long summers causing droughts and forests fires. 2018 was one of the driest summers in Europe, resulting in forest carbon sinks decreasing or even turning forests into sources in some cases. Anomalously high solar radiation also led to extreme algal blooms in the Baltic Sea. Thus the feedbacks between the climate system and GHG cycles are multi-dimensional and complex, and need inter-disciplinary research.
For this session, we invite abstracts from observational and modeling studies examining and integrating extreme changes in GHGs (biogenic and/or anthropogenic) and their feedbacks to the climate system. For example (but not limited to):
1. Aftermath of COVID-19 lockdown, emerging into the new normal.
2. Effect of forest fires in 2019 and 2020 on regional to global scale.
3. Warm and wet winter of 2019/2020 and its impact on terrestrial and marine ecosystems.
4. Dry and hot European summers and subsequent droughts since 2018.  

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). Over the past decades, emission reductions for air pollution abatement has also resulted in changes in precipitation, cloud and aerosol chemical composition, and in atmospheric deposition of anthropogenically derived nutrients to the ocean, affecting atmospheric acidity and atmospheric deposition to ecosystems. Atmospheric inputs of other toxic substances (e.g., lead, mercury, cadmium, copper, and persistent organic pollutants) into the ocean are also of concern for their impact on ocean ecosystem health. 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 acidity, atmospheric deposition, nutrient availability, marine biological productivity, and the biogeochemical cycles governing air-sea fluxes of these climate active species.

This session will address the atmospheric deposition of nutrients and toxic substances to the ocean, their 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 (in-situ and remote sensing), process studies, 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), and the International Commission on Atmospheric Chemistry and Global Pollution (ICACGP).

We welcome submissions on all aspects of tides in the ocean, atmosphere and solid Earth, from regional to global scales and covering all time scales on Earth and other planets. Tides impact many Earth system processes such as ocean mixing, global ocean circulation, ice sheet dynamics and biogeochemical processes. Tides interacting with storm surges and sea level rise can cause coastal flooding, and harnessing of tidal energy can provide a source of renewable energy. Accurate tide models are necessary for the analysis of satellite gravimetry and altimetry data, especially in light of the upcoming Surface Water Ocean Topography (SWOT) mission.
We encourage contributions on progress in numerical modelling of both surface and internal tides and assessments of their accuracy, observations of long-term changes in tides and tidal processes on global to regional scales, insights on tidal variability from global geodetic observing techniques, and research into the role of tides in shaping Earth’s evolutionary processes. We also invite submissions on tidal dynamics in estuaries, rivers and lakes.

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.

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.

Data assimilation integrates observational information into Earth system models or compartment models of the Earth system. Simulating different compartments in a coupled model includes the simulation of exchanges between different compartments: between the ocean and atmosphere, the atmosphere and the land surface, and the ocean and marine ecosystems. This coupling allows data assimilation in a single compartment to also influence other components. Cross-compartment or strongly-coupled assimilation accomplishes these by exploiting correlations between different compartments to jointly update coupled compartments. Here, particular challenges are small magnitudes of inter-compartment correlations and the disparity in the time scales between different compartments of the Earth system. From the algorithmic viewpoint, the estimation of cross-correlations by either ensembles of limited size or in parameterized form, and the nonlinearity of the dynamics pose significant challenges.
Contributions are invited on data assimilation into coupled models of Earth System components, weakly and strongly coupled data assimilation - methodology and applications, as well as computational aspects of data assimilation into Earth system models. We are further interested into contributions about the value of observations for cross-compartmental data assimilation (like observations at the interface of compartments with strong correlations to other Earth system components). The applications of interest include, but are not limited to, the solid Earth, hydrology, ocean, atmosphere, glaciology, biogeochemistry and ecosystems, and also geodesy.

The Copernicus Marine Environment Monitoring Service (CMEMS) provides regular and systematic reference information on the physical and biogeochemical states (including sea-ice and sea state) of the global ocean and the 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 datasets). CMEMS provides a sustainable response to private and public user needs, for academic, operational and private-sector activities and to support policies. After a first phase during 2014-2020 (CMEMS1), the Copernicus Marine Service enters a new phase covering 2021-2027 (CMEMS2).

The session will first focus on main achievements of CMEMS1.   This includes 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 prepare CMEMS long-term evolutions in CMEMS2:   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 CMEMS and participation from external teams is strongly encouraged (e.g. from H2020 projects relevant to CMEMS and downstream applications).

Marine pollution, such as natural and anthropogenic oil slicks, are of great concern. Surface oil slicks become a great hazard if they reach coastal or sea ice infested areas. Lower concentration levels of submerged substances, e.g., from produced water releases, can have a harmful effect on marine organisms in the long term. Operational ocean surveillance relies heavily on remote sensing data for detection, and ocean circulation models are commonly used to forecast and evaluate drift patterns and concentration changes. Localization, monitoring and slick redistribution information from remote sensing techniques is essential for a fast response and effective clean-up operation. Mapping of submerged substances relies more on ocean circulation modeling and in-situ measurements. Surveillance is still manual-labor intensive, though increased availability of free remote sensing images through, e.g. the Sentinel satellites, has opened up possibilities for developments of automated and semi-automated techniques for oil slick detection, characterization and tracking.
Within this session we welcome contributions covering all aspects of circulation and drift modelling for marine pollution as well as further developments on ocean surveillance using a range of satellites, including but not limited to synthetic aperture radar and optical sensors. Submissions with a focus on observation-model synthesis and interdisciplinary studies are particularly encouraged.

Plastic contamination is a global concern. With increasing usage and disposal of plastics, waste management is often inefficient in processing the volumes of plastic discarded. A large proportion of plastic waste accumulates in the natural environment where clean-up is difficult, if not impossible. This results in the plastic contamination persisting in the environment for many years, having the potential to cause long-term ecological harm, ultimately affecting humans.

To mitigate plastic pollution and find solutions to reduce harmful effects, a better understanding of the sources and pathways of plastics in the environment is needed. This should inform social and industrial practices, as well as advise on regulatory changes to address plastic management. This will also promote developing a roadmap towards the development and safe usage of alternative materials, to reduce environmental and health implications. The approach aims at bringing together academics from a variety of research fields and citizen science initiatives along with stakeholders from civil society and industry, as well as regulators and policymakers. The task requires collaboration across disciplines, from environmental sciences, including biology and chemistry, geosciences, atmospheric sciences and oceanography, to materials science, social sciences and economics.

This session will address the linkages and cross-disciplinary collaborations required for effective progress in this field. We specifically invite presentations featuring successes and challenges in collaboration between academia, industry and regulators. Presentations on tracking plastics and on elucidating connecting mechanisms from human activities through to environmental abundance and impact are encouraged. Studies on biota-plastic interactions, plastic fluxes linked to human activities and environmental changes (from synoptic events to climate change) and studies linking plastic characteristics to toxicological impacts (chemistry, materials science and ecotoxicology) are welcomed.

This is a linked session co-organised and co-designed with a session at the annual meeting of SETAC Europe (Society of Environmental Toxicology and Chemistry), by connected convenor teams, to ensure full integration and input across disciplines. Outputs from the linked sessions will be disseminated widely across SETAC and EGU members through online resources, with a view to effective knowledge sharing and building collaborations.

Plastic contamination has been reported in all realms of the environment from the tropics to the polar oceans. Our poor knowledge of plastics sources, pathways and hot spots of accumulation prevents an assessment of risks to ecosystems, human health, and the development of appropriate mitigation strategies. In order to understand current distributions of plastics and the way they evolve in space and time, much better observations and common consistent measuring methods are required but simultaneously, observations must be systematically combined with computational models. The session aims to set up a forum for multi-disciplinary discussions to create a global picture of plastic contamination in the environment and to suggest approaches for future research, monitoring and mitigation of plastic pollutions impacts. The session will provide a platform for discussions to advise policy and industry on the best ways to assess potential harm to the environment and human health from this contaminant.
This session will draw together research on plastic contamination across all sizes of plastics from shelf seas to the deep ocean including ice-covered seas. The forum will facilitate combining observations with state-of-the-art computational modelling to promote the fast advance of research and improve our understanding of how plastic pollution affects environments worldwide. We invite contributions on field and remote observations, laboratory experiments, novel modelling approaches, related scientific initiatives and projects. New ideas for citizen-science involvement and for mitigation strategies to reduce plastic contamination of the environment are especially welcome.

Global plastic production has increased exponentially since the fifties, with 359 million metric tons manufactured in 2018 alone. Nearly 20% of this production took place within Europe, where at least half of discarded plastics collected for ‘recycling’ were instead exported to China and SE Asia. Every year, an increasing proportion of these plastics (in the order of millions of tons) enter and accumulate in our waterways and oceans. In riverine and marine systems, the presence of micro to macroplastic debris has generated a growing and persistent threat to the environment and ecosystems, as well as an urgent and multi-dimensional challenge for our society.

Methods for resource-efficient and large-scale detection and monitoring of plastic litter are still relatively new. However, in the last few years, they have blossomed across technologies and environments - from mounted cameras to drones to satellites, and from lakes and rivers to coastal waters and open oceans. These new technologies can be crucial to fill in the gaps between limited in situ observations and global models, allowing coverage across fine as well as large spatial scales, and over long time periods. We invite abstracts describing the use of cameras, drones, satellites and other remote sensing techniques to observe and monitor riverine and marine plastics. We also welcome work describing or demonstrating new approaches, methods and algorithms to improve the use of cameras and sensors for plastic detection on (and in) water.

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

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

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

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 soliton 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.

Lagrangian trajectories are currently used for a vast range of purposes in ocean and atmosphere sciences. Examples include studying the connectivity of ocean basins, forecasting the spreading of ash clouds, mapping global ocean diffusivities, observing the deep ocean, or tracing plastics and other forms of pollutants in the ocean, etc. There is thus a need for numerical models capable of simulating Lagrangian particles in the ocean and atmosphere as well as accurate methods for analysing the data from surface drifters, floats, and simulated particles.

This session aims at bringing together scientists working on all sorts of Lagrangian methods, e.g. observed or simulated particles in the atmosphere and ocean, and a variety of use cases e.g. studying oceanic mixing/diffusivity, tracing pollution in the atmosphere or ocean, iceberg tracking etc. We welcome presentations on e.g.:

* Connectivity and pathways of air- or water-masses in the atmosphere and the ocean
* Quantifying water mass transformations and fluxes between regions in the ocean
* Development of Lagrangian particle-tracking algorithms and approaches to model particles with active behaviours, e.g. icebergs, fish, ash clouds, plastics etc.
* New methods and tools to analyse observed or simulated Lagrangian particles, e.g. diffusivity, spreading rates, etc.
* New developments in in-situ observations such as balloons, surface drifters or floats.

Tsunamis can produce catastrophic damage on vulnerable coastlines, essentially following major earthquakes, landslides or atmospheric disturbances. After the disastrous tsunamis in 2004 and 2011, tsunami science has grown significantly, opening new fields of research for various domains, and also in regions where the tsunami hazard was previously underestimated.
Numerical modeling, complemented with laboratory experiments, are essential to quantify the tsunami hazard. To this end, it is essential to rely on complete databases of past tsunami observations, including both historical events and results of paleotsunami investigations. Furthermore, a robust hazard analysis has to take into account uncertainties and probabilities with the more advanced approaches such as PTHA.
Because the vulnerability of populations, of infrastructures and of the built environment in coastal zones increases, integrated plans for tsunami risk prevention and mitigation should be encouraged in any exposed coastline, consistent with the procedures now in place in a growing number of Tsunami Warning System.

The tsunami session welcomes multidisciplinary contributions covering any of the aspects mentioned here, encompassing field data, regional hazard studies, observation databases, numerical modeling, risk studies, real time networks, operational tools and procedures towards a most efficient warning.

A focus on recent tsunami events all over the globe is encouraged, as well as on the achievements of recent research and operational projects.

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

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

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 the 2018 launched six beam photon counting laser altimeter on-board 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.

Recent years have seen significant reductions in Arctic sea ice extent, and a redistribution of sea ice in the Antarctic. Climate projections suggest a reduction of the sea ice cover in both poles, with the Arctic becoming seasonally ice free in the latter half of this century.

The scientific community is investing considerable effort in organising our current knowledge of the physical and biogeochemical properties of sea ice, exploring poorly understood sea ice processes, and forecasting future changes of the sea ice cover.

In this session, we invite contributions regarding all aspects of sea ice science and sea ice-climate interactions, including snow and sea ice thermodynamics and dynamics, sea ice-atmosphere and sea ice-ocean interactions, sea ice biological and chemical processes, and sea ice models. A focus on emerging processes and implications is particularly welcome.

Sea-level rise (SLR) is highly variable in space and time, as it results from a combination of many processes working at different temporal and spatial scales. In the 20th century, SLR was mainly caused by oceanic thermal expansion and the mass loss of glaciers. In recent decades, however, the two ice sheets of Antarctica and Greenland have increasingly contributed to SLR. As highlighted in the last Intergovernmental Panel on Climate Change assessment, the main uncertainty in projections of future SLR is our limited ability to model the dynamics of the Antarctic and Greenland ice sheets and robustly predict the potential emergence and rate of their collapse. Although the relative contribution of ice sheet mass loss to SLR will increase over the 21st Century, glaciers will continue to make a significant SLR contribution that must also be better quantified. Moreover, local SLR differs from global-mean change, so it is important to better understand and quantify the regional coastal implications in order to support relevant mitigation and adaptation strategies. This session aims at bridging the gap between scientific communities interested in projecting changes in the land-based cryosphere,
with fully quantified uncertainties, in order to produce robust global, regional and local projections of SLR on timescales from decades to multi-centennial and their implications.

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.

Detailed maps of the seabed, portraying the spatial distribution of geomorphic features, substrates, and habitats, are used for a wide range of environmental, scientific, and economic maritime applications. These maps are the scientific basis for informed ocean and coastal management at local to regional scales, and thereby provide cornerstones to national and international nature-conservation policies. Fundamental to seabed mapping are acoustic remote-sensing technologies, which include singlebeam and multibeam echosounders, along with sidescan, interferometric, and synthetic-aperture sonars. These are deployed on various platforms including manned and unmanned surface and underwater vessels. In relatively shallow and transparent waters, optical methods such as aircraft and satellite-based remote sensing and LiDAR are employed with increasing success. Innovative processing and classification software, image analysis, machine and deep-learning applications are advancing developments in seabed-recognition techniques, the application of which is increasing the resolution and confidence in the maps produced. We welcome submissions that provide insights into new developments, methods, and results in the field of seabed mapping and classification. This session also aims to showcase a range of applications for these datasets.

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 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.

Internal gravity waves (IGWs) still pose major questions both to the atmospheric and ocean sciences, and to stellar physics. Important issues are IGW radiation from their various relevant sources, IGW reflection at boundaries, their propagation through and interaction with a larger-scale flow, wave-induced mean flow, wave-wave interactions in general, wave breaking and its implications for mixing, and the parameterization of these processes in models not explicitly resolving IGWs. The observational record, both on a global scale and with respect to local small-scale processes, is not yet sufficiently able to yield appropriate constraints. The session is intended to bring together experts from all fields of geophysical and astrophysical fluid dynamics working on related problems. Presentations on theoretical, modelling, experimental, and observational work with regard to all aspects of IGWs are most welcome, including those on major collaborative projects, such as MS-GWaves.

This session invites presentations on simulations of weather and climate models running at high resolution. This includes state-of-the-art storm-resolving simulations (e.g. from the DYAMAND project), high-resolution climate models (e.g. from the PRIMAVERA project) but also large-eddy simulations and high-resolution ocean modelling. Presentations can cover developments to improve model fidelity (e.g. via improved parametrisations), detailed studies of modelled phenomena (e.g. tropical cyclones) but also computational and model development challenges (e.g. the use of GPUs, domain-specific languages or the development of new dynamical cores).

This session aims at fostering discussions on the physical processes at work at the air-sea interface, including their observation and representation in coupled numerical models, as well as their impact of air-sea fluxes. Examples of such processes are 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.

This session is thus intended for (i) contributions presenting observational or theoretical aspects of the processes described above and their impact on energy, water, momentum, gas and aerosols exchanges at the interface; and (ii) contributions focusing on the mathematical and algorithmic methods used to represent these processes in coupled ocean-atmosphere models.

This session seeks observational studies based on recent field campaigns or satellite remote sensing. This session also aims to gather studies using numerical models of any level of complexity (from highly idealized to realistic) and any resolution from Large Eddy Simulation (LES) to global circulation models. Studies describing the impact of the air-sea interaction physical processes on the mean global or regional climates and variability representation are also welcome.

Publishing your research in a peer reviewed journal is essential for a career in research. The EGU Journals are fully open access which is great, but the open discussion can be daunting for first time submitters and early career scientists. This short course will cover all you need to know about the publication process from start to end for EGU journals, and give you a chance to ask the editors some questions. This includes: what the editor looks for in your submitted paper, how to deal with corrections or rejections, and how best to communicate with your reviewers and editors for a smooth transition from submission to publication. An open discussion will be served to give you time for questions to the editors,and for them to suggest some ‘top tips’ for a successful publication. This course is aimed at early-career researchers who are about to step into the publication process, and those who are yet to publish in EGU journals. Similarly, this course will be of interest to those looking to get involved in the peer-review process through reviewing and editing.

The Intergovernmental Panel on Climate Change (IPCC) is currently in its sixth Assessment Report cycle (AR6). Three Special Reports (on Global warming of 1.5°C, Oceans and Cryosphere in a Changing Climate, and Climate Change and Land) have already been published in 2018 and 2019 and the main reports of the three working groups should be released before the end of 2021.

But how are IPCC reports produced? How many scientists are involved? And what’s it really like to be a scientist working in this process, right at the interface of science and policy? And how can you help as a scientist?

In this short course, we will reveal the behind-the-scenes nature of this multidisciplinary effort to provide evidence-based policy at a global scale. We will highlight the different products of the IPCC reports; which ones you can use for your research, which for your teaching, and which for your science communication. We might even have some spare copies of the Special Report Summary for Policymakers to give away (if we have an in-person meeting).

After presentations, there will be a Q&A for a chance to have a more in-depth discussion. For more information on AR6 and the IPCC in general, please visit the IPCC website: https://www.ipcc.ch/

Computer models are essential tools in the earth system sciences. They underpin our search for understanding the earth system functioning and support decision-making across spatial and temporal scales. Predictions of computer models though are conditional on a range of assumptions and input data that are often largely uncertain. These uncertainties stem from various sources, including: limited understanding of earth systems processes and interactions; simplified representation of spatial heterogeneity in our models; sparse and noisy data. To understand the implications of uncertainty and environmental variability on the identification and use of earth system models, we can rely on increasingly powerful Uncertainty and Sensitivity Analysis methods. In this short course we will

- review the key sources of uncertainty in earth system models (data, structure, parameters, etc.; epistemic vs aleatory; ...)

- discuss why considering uncertainty is important: implications for model calibration, evalluation and use in decision-making

- learn the basics of forward propagation of uncertainty (Monte Carlo simulation) and sensitivity analysis

- review some case study applications and what the modelling communities have learnt from these applications
- provide some 'hands-on' experience using the widely applicable SAFE toolbox (available in matlab/R/python).
The course will comprise a lecture-type introduction with discussion (1 hour 45 min) and a hands-on session (1 hour 45 min)

Numerical models used for weather and climate prediction have traditionally been formulated in a deterministic manner. In other words, given a particular state of the resolved scale variables, the most likely forcing from sub-grid scale motions and parametrised processes is estimated and used to predict the evolution of the large-scale flow. However, knowledge uncertainties, necessary simplifications in representing the physical processes in numerical models, and the lack of scale-separation in the Earth System mean that this approach is a large source of error in forecasts. Over recent years, an alternative paradigm has developed: the use of stochastic techniques to represent the effects of uncertain small-scale and parametrised processes. Instead of predicting the most likely forcing effect of these processes on the resolved scales, a Monte-Carlo approach is used. Integrations of the numerical model sample possible realisations of the forcing.

Stochastic parametrisations are now the norm in ensemble weather and seasonal forecasts worldwide. By accounting for uncertainty in the forecast due to the limitations of numerical models, stochastic parametrisations improve the reliability of ensemble forecasts. We are now seeing their adaptation for use in climate models, with stochastic parametrisations being developed to represent a wide range of processes in the Earth System, including processes in the atmosphere, oceans, and land surface.

This course will introduce the art and science of stochastic parametrisation, including

> Purpose: model uncertainty, ensemble forecasting, climate applications
> Foundations: stochastic processes
> Theory: how to design a stochastic scheme
> Realisation: the path from a well-designed scheme to an operational implementation in a numerical model

This course is aimed at PhD students, Early Career Scientists, and all those interested in an overview of key concepts in stochastic parametrisation. The course will be taught through a combination of presentations and interactive exercises using python notebooks. No prior knowledge of python is necessary.

The climate is highly variable over wide ranges of scale in both space and time so that the amplitude of changes systematically depends on the scale of observations. As a consequence, climate variations recorded in time series or spatial distributions, which are produced through modelling or empirical analyses are inextricably linked to their space-time scales and is a significant part of the uncertainties in the proxy approaches. Rather than treating the variability as a limitation to our knowledge, as a distraction from mechanistic explanations and theories, in this course the variability is treated as an important, fundamental aspect of the climate dynamics that must be understood and modelled in its own right. Long considered as no more than an uninteresting spectral “background”, modern data shows that in fact it contains most of the variance.

We review techniques that make it possible to systematically analyse and model the variability of instrumental and proxy data, the inferred climate variables and the outputs of GCM’s. These analyses enable us to cover wide ranges of scale in both space and in time - and jointly in space-time - without trivializing the links between the measurements, proxies and the state variables (temperature, precipitation etc.). They promise to systematically allow us to compare model outputs with data, to understand the climate processes from small to large and from fast to slow. Specific tools that will be covered include spectral analysis, scaling fluctuation analysis, wavelets, fractals, multifractals, and stochastic modeling; we discuss corresponding software. We also include new developments in the Fractional Energy Balance Equation approach that combines energy and scale symmetries.

The climate system as a whole can be viewed as a highly complex thermal/heat engine, in which numerous processes continuously interact to transform heat into work and vice-versa. As any physical system, the climate system obeys the basic laws of thermodynamics, and we may therefore expect the tools of non-equilibrium thermodynamics to be particularly useful in describing and synthesising its properties. The main aim of this short course will be twofold. Part 1 will provide an advanced introduction to the fundamentals of equilibrium and non-equilibrium thermodynamics, irreversible processes and energetics of multicomponent stratified fluids. Part 2 will illustrate the usefulness of this viewpoint to summarize the main features of the climate system in terms of thermodynamic cycles, as well as a diagnostic tool to constrain the behavior of climate models. Although the aim is for this to be a self-contained module, some basic knowledge of the subject would be beneficial to the participants. Registration is not needed, but indication of interest would be helpful for planning purposes.

EUMETSAT offers over 35 years of meteorological satellite data. New data consistency with previous satellites is ensured by intercalibration and reprocessing. This is a valuable resource for the geoscience communities. EUMETSAT produces 26% of the Essential Climate Variable records identified by the Global Climate Observing System that can be observed from space.

With the new satellite programmes, the volume and complexity of the data products will increase significantly, making it unfeasible for traditional workflows, relying on accessing local data holdings, to exploit these observations. EUMETSAT’s new Data Services, the subject of this course, address this issue.

In this short course you will learn:
• what EUMETSAT offers the geoscience communities within Europe (Data Store, Data Tailor, and visualisation service)
• how to set up access and how to use the GUIs and APIs, Jupiter notebooks and documentation will be available to take away
• about EUMETCast - EUMETSAT's multicast feed available through satellite and terrestrial networks (GEANT)
• about EUMETSAT's hosted processing and its availability to the geoscience community

The Data Store provides online access for directly downloading satellite data via a web-based user interface and APIs usable in processing chains. Users can download the data in its original format or customise it before download by invoking the Data Tailor Service. The View Service provides access via standard OGC Web Map, Web Coverage and Web Feature Services (WMS, WCS, WFS) which visualise data available in the Data Store. It is accessible via a web-based interface and APIs allowing the integration of visualisations in end-user applications.

This short course is open to all attending the EGU and will give you an introduction in how to use the services. User guides will be made available before the event and there will be time for questions and answers.

Satellite data provides information on the marine environment that can be used for many applications – from water quality and early warning systems, to climate change studies and marine spatial planning. The most modern generation of satellites offer improvements in spatial and temporal resolution as well as a constantly evolving suite of products.

Data from the European Union Copernicus programme is open and free for everyone to use however they wish - whether from academic, governance, or commercial backgrounds. The programme has an operational focus, with satellite constellations offering continuity of service for the foreseeable future. There is also a growing availability of open source tools that can be used to work with this data.

This short course is an opportunity to learn about the marine data from the Copernicus Sentinel-3 satellites provided by EUMETSAT and downstream services including the Copernicus Marine Environment Monitoring service (CMEMS). The short course will be interactive, using the WEkEO DIAS hosted processing, Sentinel Applications Platform (SNAP) software, and Python programming. The short course will also offer some presentations and practical demonstrations focusing on the Copernicus Marine Service portfolio. This part is an occasion to discover the catalogue of products, to learn how to find the relevant data or information and the different way to download the data.