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Hydrographic data are analyzed for the broad continental shelf of the Bellingshausen Sea, which is host to a number of rapidly thinning ice shelves. The flow of warm Circumpolar Deep Water (CDW) onto the continental shelf is observed in the two major glacially carved troughs, the Belgica and Latady troughs. Using ship-based measurements of potential temperature, salinity, and dissolved oxygen, collected across several coast-to-coast transects over the Bellingshausen shelf in 2007, the velocity and circulation patterns are inferred based on geostrophic balance and further constrained by the tracer and mass budgets. Meltwater was observed at the surface and at intermediate depth toward the western side of the continental shelf, collocated with inferred outflows. The maximum conversion rate from the dense CDW to lighter water masses by mixing with glacial meltwater is estimated to be 0.37 ± 0.1 Sv in both depth and potential density spaces. This diapycnal overturning is comparable to previous estimates made in the neighboring Amundsen Sea, highlighting the overlooked importance of water mass modification and meltwater production associated with glacial melting in the Bellingshausen Sea. 

The stability of the West Antarctic Ice Sheet (WAIS) depends on ocean heat transport toward its base and remains a source of uncertainty in sea level rise prediction. The Antarctic Slope Current (ASC), a major boundary current of the ocean's global circulation, serves as a dynamic gateway for heat transport toward Antarctica. Here, we use observations collected from the Bellingshausen Sea to propose a mechanistic explanation for the initiation of the westward-flowing ASC. Waters modified throughout the Bellingshausen Sea by ocean-sea-ice and ocean-ice-shelf interactions are exported to the continental slope in a narrow, topographically steered western boundary current. This focused outflow produces a localized front at the shelf break that supports the emerging ASC. This mechanism emphasizes the importance of buoyancy forcing, integrated over the continental shelf, as opposed to local wind forcing, in the generation mechanism and suggests the potential for remote control of melt rates of WAIS' largest ice shelves.