The Observed Seasonal Cycle of Submesoscale Processes in the Antarctic Marginal Ice Zone and Linkages with Sea Ice Cover

Louise C Biddle1, Sebastiaan Swart1 and Marcel du Plessis2, (1)University of Gothenburg, Department of Marine Sciences, Gothenburg, Sweden, (2)University of Cape Town, Department of Oceanography, Cape Town, South Africa
Abstract:
Submesoscale flows are energetic processes in the upper ocean that occur at scales of a few kilometers and can cause high frequency variability in the mixed layer depth. These phenomena are important to climate because they can strongly impact vertical motions of heat, carbon and biogeochemical properties between the surface and deep ocean, yet their presence and magnitude are poorly understood in the Antarctic Sea Ice Zone (SIZ) and under sea ice due to a lack of observations. Through a combination of tagged mammals and ocean gliders, we present estimates of the magnitude and seasonality of submesoscale processes in the Antarctic SIZ. We find that there is a strong seasonal cycle in the magnitude of submesoscale flows (180 Wm-2) and show linkages between sea ice cover and submesoscale activity. Periods of increased variability in sea ice concentration, likely linked to increased occurrence of leads, are associated with restratification of the upper ocean through submesoscale fluxes. These findings have implications for understanding the magnitude and variability of upper ocean stratification and therefore the ability to exchange key climate-relevant properties, such as heat and carbon, between the air-sea-ice interfaces in the Antarctic SIZ.