Submeso-scale Mixing Features in the Gerlache Strait Bays (Antarctica)

Abstract

Measurements of turbulence in the ocean are sparse, especially in environments such as Antarctica. Here we map the spatial distribution of diapycnal diffusivities and the water column characteristics across the three main bays in the Gerlache Strait on the western side of the Antarctic Peninsula. The measurements were recorded during the Fifth Colombian Antarctic Expedition, 2018-2019, using a Vertical Microstructure Profiler in free fall for the first 400 m depth, to record fluctuations of vertical shear at dissipation scales (10-3 – 103m). Diapycnal diffusivities are higher by 1-2 orders of magnitude in the Gerlache mainstream compared with the interior bays, with values from O (log10kρ = -3 m2 s -1) to O (log10kρ = -5 m2s -1) respectively over the upper 400 m. The highest mixing values were recorded in the southern section of Gerlache Strait (Flandes Bay) compared to the northern one (Charlotte Bay), indicating better wellmixed water in the south. Observed Hot Spots of higher turbulence levels may be associated with the interaction of the entrance of the Upper Circumpolar Depth Water, the Antarctic Surface Water, and the Weddell Sea Deep Waters with resident waters and topography.