Ice Shelf Basal Melt and Influence on Dense Water Outflow in the Southern Weddell Sea

We use new observations of stable water isotopes from a research cruise in early 2017 to highlight ocean-ice interactions occurring under Filchner-Ronne Ice Shelf, the largest Antarctic ice shelf. In particular, we investigate the properties of Ice ShelfWater with temperature lower than the surface freezing point, in the Filchner Depression. We identify two main flavors of Ice ShelfWater emerging from beneath the Filchner Ice Shelf, which originate from High Salinity ShelfWater end members with distinct characteristics. Furthermore, these two High Salinity ShelfWater end members interact with areas of the ice shelves with different basal properties to produce different versions of Ice ShelfWater. These water masses are associated with different rates of basal melting and refreezing, which we quantify. Ice Shelf Water types that flow out of the ice shelf cavity are composed of 0.4% of mass from ice shelf (melt minus freeze) when sampled at the front of Filchner Ice Shelf. The slightly lighter Ice ShelfWater version mixes directly with ambient water masses as it flows northward on the continental shelf. The resulting Ice Shelf Water mixture with temperature below the surface freezing point ultimately sinks along the continental slope into the deep ocean, as a precursor of theWeddell Sea bottom waters.