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Abstract

The contribution of mesoscale eddies to heat transport can be important in regions with high eddy kinetic energy such as the Southern Ocean. However, there are large gaps in our understanding of this contribution towards seasonally sea ice-covered regions due to the lack of observations and resolution in ocean and climate models. Using an idealized configuration of the Southern Ocean at 10 km horizontal resolution, we investigate the contribution of the resolved mesoscale, that is all transient processes, to the total heat transport towards and under the sea ice in the Southern Ocean. We find that the southward total heat transport is mainly driven by the transient heat transport. We then extract the heat transport by coherent mesoscale eddies from that of all transient processes using an eddy detection and tracking algorithm. Coherent eddies contribute 40-50% to the meridional transient heat transport depending on the latitude. The transient heat transport can almost entirely be attributed to advective processes. Stirring of heat induced by coherent eddies accounts for the majority of meridional heat transport by these eddies. The majority of the heat transport across the ice edge by all transient processes occurs below the mixed layer and about two thirds of this heat is then upwelled across the base of the winter mixed layer with 40-50% of this heat being brought by coherent eddies. Within the mixed layer, the importance of these eddies for the vertical heat transport towards the pack ice is comparatively smaller at 20-30%.