Anne Marie Treguier

The ocean and sea ice are central to Earth's climate system, influencing global heat and carbon cycles, weather patterns, and sea level rise. Recent decades have seen rapid advances in Earth System Models (ESMs), but limitations remain in simulating and comparing key oceanic and cryospheric processes across models. A recurring challenge in model intercomparison efforts like the Coupled Model Intercomparison Project (CMIP) is determining the output variables that best represent essential mechanisms while remaining manageable in volume and complexity. Here we present the CMIP7 ocean and sea ice data request, developed through an international, community-based process to prioritize variables for model output. We identify seven opportunities – science-based use cases spanning ocean and cryosphere drivers and responses, paleoclimate, polar amplification, extremes, wind waves, and rapid model evaluation – to guide variable selection and temporal resolution. To address these opportunities, we request new high-frequency and depth-integrated variables, support improved diagnostics of ocean heat uptake, sea ice processes, and model-observation comparison, and build on lessons from CMIP6. Our approach enables targeted, efficient, and transparent data curation to support a wide range of users, from model developers to policymakers. This effort reflects a growing need for more sophisticated, integrative model outputs that address pressing climate questions, including regional extremes and tipping points, while laying the groundwork for future modeling developments.

This study investigates the influence of model resolution on the representation of Antarctic Intermediate Water (AAIW) hydrographic properties and the role of eddies in the meridional transport of salt using three simulations from the HadGEM3‐GC3.1 HighResMIP family with varying ocean resolutions: the 1° LL model (parameterized eddies), the 1/4° MM model (eddy‐present), and the 1/12° HH model (eddy‐rich). The control‐1950 simulation is compared with the WOA18 climatology. Results show that increasing model resolution improves the representation of AAIW core properties (temperature, salinity, and density) and its northward extent. The LL model shows a restricted low‐salinity tongue compared to observations, whereas the MM and HH models are more aligned with observations. Regions of high eddy kinetic energy coincide with major AAIW pathways in the MM and HH models, while the LL model is not able to capture the fine scale of the western boundary currents. The meridional salt transport is decomposed into its mean and eddy component and a compensation of both terms is found in MM and HH. The intermediate layer contributes to close to 30% of the total northward salt transport. Although total and eddy meridional salt transports are similar between MM and HH for the intermediate layer, the HH model contains more coherent eddies with greater westward propagation, suggesting distinct underlying mechanisms of salt transport. The findings highlight the limitations of the LL model in reproducing AAIW properties and circulation, with major improvements in the MM and HH models.

While EGU is celebrating the 25-year anniversary of Interactive Open Access Publishing, we at Ocean Science just celebrated our 20-year anniversary last year. We did this with a well-visited reception at last year’s General Assembly and with an extraordinary jubilee special issue on reviews of and perspectives on the last 20 years and the coming 20 years. These influential reviews will at the same time complement the EGU Encyclopedia of Geosciences. During these 20 years we have become one of the leading publications for oceanic research, where the number of published articles has increased steadily to 174 in 2025. We accept submissions in all fields of ocean research and across all spatial and temporal scales and methods, including physical, chemical, biogeochemical and biological ocean processes and interactions, marine ecology, mesoscale-to-submesoscale dynamics, benthic and sediment processes and fluxes between the ocean, atmosphere and land. The approach taken can be common observations in oceanography, but also remote sensing, instrument development and techniques, laboratory studies, analytic theory, numerical models, data assimilation and operational oceanography. Our overall motto is that a paper should teach us something new about the oceans. Manuscript types considered are Research Articles, OS Letters, Review Articles, Technical Notes, Opinions and Commentaries/Replies.Currently, we have 24 editors, including the four co-editors-in-chief. The editors all have their specific expertise which drives the kinds of manuscripts that they handle. We are always open for new editors, depending on the expertise needed. We are also open to new referees, that is, early career scientists with experience in publishing; those interested can apply by filling in the dedicated online form.Our journal is in constant development, both intern as part of the EGU/Copernicus family, and within the science community. We would like to involve as many people as reasonably possible. If you are interested to be part of this development in any way, do not hesitate to contact us at the general assembly or by email.

This study investigates the influence of model resolution on the representation of Antarctic Intermediate Water (AAIW) hydrographic properties and the role of eddies in the meridional transport of salt using three simulations from the HadGEM3-GC3.1 HighResMIP family with varying ocean resolutions: the 1° LL model (parameterised eddies), the 1/4° MM model (eddy-present), and the 1/12° HH model (eddy-rich). The control-1950 simulation is compared with the WOA18 climatology. Results show that increasing model resolution improves the representation of AAIW core properties (temperature, salinity, and density) and its northward extent. The LL model shows a restricted low-salinity tongue compared to observations, whereas the MM and HH models are more aligned with observations. Regions of high eddy kinetic energy coincide with major AAIW pathways in the MM and HH models, while the LL model is not able to capture the fine scale of the western boundary currents. The meridional salt transport is decomposed into its mean and eddy component and a compensation of both terms is found in MM and HH. The intermediate layer contributes to close to 30% of the total northward salt transport. Although total and eddy meridional salt transports are similar between MM and HH for the intermediate layer, the HH model contains more coherent eddies with greater westward propagation, suggesting distinct underlying mechanisms of salt transport. The findings highlight the limitations of the LL model in reproducing AAIW properties and circulation, with major improvements in the MM and HH models.

The seasonality of Arctic sea ice cover significantly influences heat, salt, buoyancy fluxes, ocean‐ice stresses, and the potential and kinetic energy stored in the ocean mixed layer. This study examines the seasonal variability of oceanic scales of motion and cross‐scale flux of kinetic energy in the seasonally ice‐covered Arctic, using a high‐resolution, idealized coupled ocean‐sea ice model. Our simulations demonstrate pronounced seasonality in the scales of oceanic motion within the mixed layer, governed by distinct mechanisms during summer and winter. In summer, the inverse energy cascade transfers kinetic energy from the submesoscale toward the mesoscale range of motions. In winter, ice‐induced dissipation suppresses kinetic energy and mesoscale motions, only allowing the persistence of submesoscale features. These results underscore the critical role of sea ice in modulating the seasonal dynamics of oceanic motion and their dominant scales, a behavior markedly different from that in the open ocean. Thus, understanding these coupled processes is essential for improving predictions of the ocean's energy evolution as the Arctic transitions toward a summer ice‐free regime.

Recent advances in numerical modeling have enabled km‐scale climate simulations, improving global climate representation and local‐scale projections, critical to climate adaptation strategies. In this context, the present study assesses the performance of such models over coastal shelf seas—key climate‐sensitive regions—in their ability to represent the sea surface temperature (SST) and air temperature. Compared to satellite and reanalysis data, the models exhibit systematic warm biases (3°C in SST, 1.5°C in air temperature) in summer across several shelf seas: the European shelf, the Gulf of Maine, the Yellow sea, the Arctic and Patagonian shelves. These biases strongly correlate with tidal mixing fronts, driven by the dissipation of the barotropic tide and identified by the Simpson‐Hunter parameter. These findings suggest that missing tidal mixing is a significant error source on coastal shelves, highlighting the need for improved ocean mixing representations to enhance model accuracy.

The ocean and sea ice are central to Earth's climate system, influencing global heat and carbon cycles, weather patterns, and sea level rise. Recent decades have seen rapid advances in Earth System Models (ESMs), but limitations remain in simulating and comparing key oceanic and cryospheric processes across models. A recurring challenge in model intercomparison efforts like the Coupled Model Intercomparison Project (CMIP) is determining the output variables that best represent essential mechanisms while remaining manageable in volume and complexity. Here we present the CMIP7 ocean and sea ice data request, developed through an international, community-based process to prioritize variables for model output. We identify seven opportunities—science-based use cases spanning ocean and cryosphere drivers and responses, paleoclimate, polar amplification, extremes, wind waves, and rapid model evaluation—to guide variable selection and temporal resolution. To address these opportunities we request new high-frequency and depth-integrated variables, support improved diagnostics of ocean heat uptake, sea ice processes, and model-observation comparison, and build on lessons from CMIP6. Our approach enables targeted, efficient, and transparent data curation to support a wide range of users, from model developers to policymakers. This effort reflects a growing need for more sophisticated, integrative model outputs that address pressing climate questions, including regional extremes and tipping points, while laying the groundwork for future modeling developments.

The ocean and sea ice are central to Earth's climate system, influencing global heat and carbon cycles, weather patterns, and sea level rise. Recent decades have seen rapid advances in Earth System Models (ESMs), but limitations remain in simulating and comparing key oceanic and cryospheric processes across models. A recurring challenge in model intercomparison efforts like the Coupled Model Intercomparison Project (CMIP) is determining the output variables that best represent essential mechanisms while remaining manageable in volume and complexity. Here we present the CMIP7 ocean and sea ice data request, developed through an international, community-based process to prioritize variables for model output. We identify seven opportunities—science-based use cases spanning ocean and cryosphere drivers and responses, paleoclimate, polar amplification, extremes, wind waves, and rapid model evaluation—to guide variable selection and temporal resolution. To address these opportunities we request new high-frequency and depth-integrated variables, support improved diagnostics of ocean heat uptake, sea ice processes, and model-observation comparison, and build on lessons from CMIP6. Our approach enables targeted, efficient, and transparent data curation to support a wide range of users, from model developers to policymakers. This effort reflects a growing need for more sophisticated, integrative model outputs that address pressing climate questions, including regional extremes and tipping points, while laying the groundwork for future modeling developments.

The ocean and sea ice are central to Earth's climate system, influencing global heat and carbon cycles, weather patterns, and sea level rise. Recent decades have seen rapid advances in Earth System Models (ESMs), but limitations remain in simulating and comparing key oceanic and cryospheric processes across models. A recurring challenge in model intercomparison efforts like the Coupled Model Intercomparison Project (CMIP) is determining the output variables that best represent essential mechanisms while remaining manageable in volume and complexity. Here we present the CMIP7 ocean and sea ice data request, developed through an international, community-based process to prioritize variables for model output. We identify seven opportunities—science-based use cases spanning ocean and cryosphere drivers and responses, paleoclimate, polar amplification, extremes, wind waves, and rapid model evaluation—to guide variable selection and temporal resolution. To address these opportunities we request new high-frequency and depth-integrated variables, support improved diagnostics of ocean heat uptake, sea ice processes, and model-observation comparison, and build on lessons from CMIP6. Our approach enables targeted, efficient, and transparent data curation to support a wide range of users, from model developers to policymakers. This effort reflects a growing need for more sophisticated, integrative model outputs that address pressing climate questions, including regional extremes and tipping points, while laying the groundwork for future modeling developments.

The ocean and sea ice are central to Earth's climate system, influencing global heat and carbon cycles, weather patterns, and sea level rise. Recent decades have seen rapid advances in Earth System Models (ESMs), but limitations remain in simulating and comparing key oceanic and cryospheric processes across models. A recurring challenge in model intercomparison efforts like the Coupled Model Intercomparison Project (CMIP) is determining the output variables that best represent essential mechanisms while remaining manageable in volume and complexity. Here we present the CMIP7 ocean and sea ice data request, developed through an international, community-based process to prioritize variables for model output. We identify seven opportunities—science-based use cases spanning ocean and cryosphere drivers and responses, paleoclimate, polar amplification, extremes, wind waves, and rapid model evaluation—to guide variable selection and temporal resolution. To address these opportunities we request new high-frequency and depth-integrated variables, support improved diagnostics of ocean heat uptake, sea ice processes, and model-observation comparison, and build on lessons from CMIP6. Our approach enables targeted, efficient, and transparent data curation to support a wide range of users, from model developers to policymakers. This effort reflects a growing need for more sophisticated, integrative model outputs that address pressing climate questions, including regional extremes and tipping points, while laying the groundwork for future modeling developments.