Understanding the role of Antarctic sea ice in dense water formation and heat and carbon sequestration: from satellite altimetry to 'big data' analysi

The ocean is the largest carbon reservoir in the Earth system and it stores over 90% of the excess heat produced by anthropogenic activities. The rate at which both heat and carbon are absorbed by the ocean varies strongly, both in space and time, and the Southern Ocean is a key region for the uptake of both. However, we have limited skills in predicting how this will change in the future. Ice-ocean-atmosphere interactions are key in determining the rates of carbon and heat uptake by the ocean. Antarctic sea ice formation/export and circumpolar westerly winds are the dominant surface forcings in the Southern Ocean, driving the upwelling and ventilation of the dense waters that fill most of the ocean's interior and the formation of Antarctic Bottom Water, a key component of the global abyssal circulation. Polynyas - seasonal openings in the sea ice - are the other main contributors to the formation of deep and dense shelf waters around the Antarctic margins. However, Southern Ocean dynamics and circulation are poorly simulated in coupled climate models. Even state-of-the-art simulations fail to represent both ice-ocean-atmosphere interactions and biogeochemical processes adequately, and observations in these regions are scarce and patchy.

Methods

Satellite along-track altimetry data in Antarctic sea ice leads will be used to analyse the ocean's sea level inside polynyas, to identify the fingerprints of dense water formation and circulation. To this end, Sea Surface Height and Sea Height Anomaly products will be processed and analysed from both the CryoSat-2 (European Space Agency) and ICESat-2 (NASA) Polar satellite missions.

The representation of processes driving deep water formation and circulation in the Southern Ocean (such as winds and sea ice dynamics) will be assessed in state-of-the-art simulations from the 6th Coupled Model Intercomparison Project (CMIP6). This will be achieved by setting up advanced cloud-based computing capabilities (e.g. Pangeo) and...