Bathymetry of the Venable Ice Shelf from Operation IceBridge (OIB) Airborne Gravity Data

Abstract:

Future projections of Antarctic Ice Sheet stability and sea level rise depend on knowledge of continental shelf bathymetry, including that which lies beneath floating ice shelves. Bathymetry controls how ocean water circulates under floating ice, thus governing ocean-ice interactions at the grounding line. In the coastal areas of Antarctica, bathymetry is not entirely known due to ice covered waters that limit ship multibeam eco sounding (MBES) and satellite mapping. In order to map these hard-to-access regions, NASA's Operation IceBridge (OIB) collected an extensive dataset of airborne gravity data over Antarctica’s ice sheets, ice shelves, and sea ice from 2009 to 2019. Here we present a model of the bathymetry beneath the Venable Ice Shelf at the base of the Antarctic Peninsula. We use observed gravity anomaly data from the Sander Geophysics Limited (SGL) AIRGrav gravimeter, in combination with ice shelf geometry constraints from radar ice thickness data and lidar surface elevation data. Preliminary gravity inversions show deeper troughs than previously mapped in front of the Williams and Wiesnet ice streams that flow into the ice shelf. They also reveal stronger connections between the grounding line and the ice shelf front. The resulting bathymetry highlights the significance of OIB’s airborne gravity dataset as a resource for creating crucial new models of the seafloor and underscores OIB’s contributions to ice sheet models in regions where floating ice makes ship and satellite mapping difficult.