| Summary: | Air-sea-ice fluxes of heat, freshwater, and carbon in the Southern Ocean are critical to global ocean circulation and climate. During the ice-free summer months, carbon-rich Warm Deep Water (WDW) around Maud Rise in the eastern Weddell Sea is insulated from the atmosphere by a surface mixed layer and residual Winter Water layer. Fluxes across the mixed layer base control exchanges between WDW and the atmosphere, as well as determining water column stability in early winter at the onset of sea ice formation. A weakly stratified winter mixed layer could be susceptible to overturning, leading to ventilation of heat from WDW and the possible formation of an open ocean polynya, as observed over Maud Rise in the 1970s and 2016-17.We use high-resolution observations from autonomous platforms deployed during the 2022 SO-CHIC campaign to analyze the summer to winter mixed layer evolution in the Maud Rise region. 6 free-drifting UpTempO buoys collected over 12,500 hourly temperature profiles of the upper 60 m of the water column between January and June 2022. In addition, a Seaglider and Sailbuoy were deployed around Maud Rise from January to April, and 4 Argo floats remained in the region through austral summer 2023. We use ERA5 atmospheric reanalysis data to model the effect of 1-D processes on upper ocean variability, in order to distinguish the influence of synoptic storm events from submesoscale dynamics and quantify the integrated impact of each of these processes on mixed layer stratification at the onset of sea ice freeze-up.
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