Summary
Sub-ice shelf bathymetry remains a poorly known but important boundary condition for models of sub-ice shelf circulation and the distribution of basal melt and accretion. Surfacebased seismic surveys are traditionally used to determine sub-ice shelf bathymetry, however their spatial extent is limited by their cost and the accessibility of the terrain. Airborne gravity data constrained by airborne radar for ice thickness and sparse seismic observations for water and sediment-layer thicknesses have been used to produce 3D bathymetry models of subglacial lakes in Antarctica. The recent availability of long-range survey aircraft in Antarctica has made nearly all ice shelves accessible from established research stations. Similar to the application to subglacial lakes, here we show that coupled airborne radar and gravimetry may be used to improve our knowledge of bathymetry under ice shelves. In addition, we use radar reflection coefficients to evaluate the distribution of basal melt and freeze-on. We first apply the methods to a survey line covering nearly the entire width of the well-studied Ross Ice Shelf in West Antarctica where several seismic reflection shots are available to constrain the gravity observations and mature models of melt/freeze are available for comparison. We also apply the methods to Totten Glacier to illustrate how they may be applied to the unknown bathymetry and melt/freeze distribution beneath the thick floating ice offshore of East Antarctica’s deep subglacial basins.