Detailed Bathymetry of the Continental Shelf Beneath the Getz Ice Shelf, West Antarctica

The Getz Ice Shelf (GIS) produces major amounts of basal meltwater due to intrusions of warm modified Circumpolar Deep Water (mCDW) beneath the ice shelf. However, multiple cavity openings and complex geography mean that knowledge of bathymetry beneath the GIS is required to understand ice/ocean interactions. We invert NASA airborne gravity data to obtain bathymetry beneath the ice shelf. Our gravity/geology‐constrained bathymetry is a significant advance on Bedmap2 bathymetry. The sub‐ice shelf bathymetry consists of three cavities separated by topographic ridges extending from the ice shelf front to the grounding line. Passages allowing limited circulation of shallow (≲400 meters below sea level [mbsl]) water between cavities are present, but deeper water is confined to individual cavities. Within each cavity, bathymetric troughs (>900 mbsl) extend from the ice shelf front to subglacial valleys beneath the ice sheet. Our analysis of the gravity data also allows us to infer the presence of thick (>500 m) sediments near the grounding line through much of the GIS, as well as variations in the density and/or thickness of the crust underlying the ice shelf. Plain Language Summary Floating ice shelves surrounding Antarctica slow the flow of the Antarctic Ice Sheet toward the ocean. West Antarctic ice shelves, including the large Getz Ice Shelf, have thinned significantly over the past 20 years, due in part to increased flow of warming ocean water into the ocean cavities beneath them. This thinning results in acceleration of ice flowing into the ocean, so that more ice goes afloat, raising sea level. We mapped the shape of the ocean floor beneath the Getz Ice Shelf, which controls water circulation under the ice shelf. We found the ice shelf has three separate portions each with deep troughs that provide pathways for warm water to the edge of the ice sheet. Key Points Inversion of airborne gravity data for bathymetry shows the Getz Ice Shelf to consist of three separate cavities with only shallow (