In a community survey the Southern Ocean modelling community was addressed for gathering a profound basis of the current state of models, future developments and observational data needs. Based on almost 100 responses, the survey outcome is presented using conditional analysis and highlighting key science topics, major future model evolutions and, specifically, potential improvements for collaboration between the communities of modellers and observationalists. Conclusions are drawn that are anticipated to be informative of and helpful for the ongoing planning of the Antarctic InSync observational program and the next International Polar Year.

There is growing evidence that the Atlantic meridional overturning circulation (AMOC) is on course to reach a tipping point, a prospect that is increasingly shaping scientific, policy, and media discourse. Here, the authors double the length of the observed AMOC record in the North Atlantic subpolar gyre to cover 2004-2024. They find that the subpolar AMOC exhibited no weakening trend in that time. The methodology could provide a blueprint for a lightweight, reliable and sustainable subpolar AMOC observing system for the coming decades.

This paper tackles uncertainty in modelling marine primary production. This is a globally important problem that is fundamental to marine biogeochemistry and climate projections. It will likely be of broad interest within the wider oceanographic community but also beyond, as it has a broader relevance to the carbon cycle. The paper attempts to reconcile two different modelling approaches on a fundamental level.

The Surface Water and Ocean Topography (SWOT) wideswath altimeter is providing unprecedented observations of the ocean surface, enabling characterisation of mesoscale eddies at high latitudes with a resolution fine enough to capture the relevant spatial scales. Eddies are smaller in high latitudes due to the change in the Coriolis parameter. The eddies in these latitudes are, however, important influencing deep-water formation, carbon uptake, and sea-ice melt. The paper shows that the new SWOT satellite enables robust, quantitative eddy detection in polar and subpolar oceans, opening the door to global eddy climatologies in areas previously inaccessible.

This study shows that the fate of internal tide energy is not uniform but is dictated by interactions with mesoscale eddies features, affecting the intensity and distribution of energy flux. The study finds that the specific response of an internal tide—whether it propagates freely or deviates—is dually controlled by the internal tide vertical modal structure, and the ocean state it encounters together with its associated background conditions. In additions, it is also found that the redistribution of energy via intermodal transfers is governed by a hierarchy of synergistic interactions between the topographic features and the background flow of the ocean state.

Tide gauges have been critical sources for sea level research, enabling the development of tidal theory and an understanding of local variations that occur across the global oceans. Tides play important roles in a variety of oceanographic and geodetic applications; characterizing their spatial variability is valuable for applications ranging from fishing to flood risk management. Coastal characteristics of ocean tides are presented based on 3,591 high-frequency tide gauge observations. The analysis shows that 125 out of 237 long-time series show statistically significant trends in one or more tide constituents. Particularly the novel results on tidal high-water durations and tidal trends are of interest. The paper provides a global summary of a number of tidal characteristic quantities that will be useful for tide experts but also for the greater oceanographic community, in particular sea level researchers, providing insights crucial for a wide range of biogeochemical processes. It also presents insights that can be useful for local communities. This paper, along with its accompanying data, could become an important reference in the field.