Option A
The activity should improve monitoring and reporting in specific ocean areas such as at depth and in marginal areas, over the continental shelf slopes, coastal zones and polar areas. The action should combine observation analyses and models over different time scales (by making use of instrumental and proxy data), benefiting from latest advances in satellite measurements and in-situ, to improve the scientific understanding of the change and variability of ocean circulation and ocean heat content change, sea surface and subsurface conditions (temperature, salinity, sea ice, currents, deep convection), and the short- and long-term variability.  The action should advance the scientific understanding of the projected decrease of Antarctic ice and Arctic sea ice and contribute to improving model projections of future changes, of the potential connections between Arctic polar warming and sea ice loss and mid-latitude atmospheric variability.

Option B:
The action should further develop essential biogeochemical ocean monitoring indicators, EOVs and ocean ECVs. The action should support the development of the ocean component of climate models through a better representation of essential biogeochemical processes, microbe biomass and diversity and enable a better understanding of the links between ocean physical and biogeochemical variability. The action should combine GHG measurements in regions especially critical for GHG fluxes (the polar oceans, main open-ocean convection areas like the North Atlantic, southern hemisphere, coastal and marginal seas, or coastal upwelling zones) with relevant biogeochemical measurements (e.g., oxygen, nutrients, carbon) to support GHG data analyses and model simulations. The action should improve the understanding of ocean biogeochemical fluxes and turnover of carbon and nitrogen in the ocean using state of the art autonomous observation technology combined with remote-sensing. This includes quantifying fluxes between basins/regimes (e.g. Arctic to North Atlantic, or coastal to oceanic) and across boundaries (air-sea, water-sediment), as well as between chemical phases (such as inorganic to organic, particulate to dissolved). Focus should be on quantifying GHG reservoir size and change, and potential subsequent impact on GHG fluxes, ocean productivity, carbon sequestration, oxygen demand and carbonate system.

Option C:
The action should develop the integration (e.g., forcing, assimilation of boundary conditions, coupling, etc.) between climate models (physics and biogeochemistry) and ecosystem/marine habitat models to support ocean biodiversity variables and ECV development, in particular, quantifying the sensitivity of regional ecosystems responses to poorly-resolved, global, physical & biogeochemical inputs at model boundaries. The action should also identify & quantify the propagation of non-linear errors through the ecosystem models (from physics through biogeochemistry and to the highest trophic levels), including through better integration of numerical & statistical approaches allowing improved forecasting. The action should advance our scientific understanding of how extremes affect organisms and ecosystems. Αdvances should be made with regard to closing gaps in our understanding of the factors controlling biological, genetic and functional diversity, food-web interactions and relationships between different ecosystem constituents (trophic links, symbiosis, parasitism, etc.).

Further details in the work programme p. 410-415