Bathymetry and Geology under Antarctic Ice Shelves from Aerogeophysics and Direct Constraints

Abstract:

Bathymetry of the cavity beneath ice shelves around Antarctica is a critical element of the ice-ocean-earth system but an elusive parameter to constrain with the coverage, accuracy, and resolution required for numerical models of ice-ocean interactions. Significant advances in sub-ice shelf mapping have been made over the last decade by major international efforts that have flown gravity surveys over the margins of the Antarctic ice sheet and modeled sub-ice shelf bathymetry. The combination of aerogeophysical data with direct measurements of bathymetry beneath ice shelves and from surrounding areas is a powerful tool to improve our knowledge of these critical regions and has substantially changed our maps of the Antarctic margin.

Using examples from the Operation IceBridge and Rosetta-Ice surveys, we present new gravity inversions from sparsely-surveyed regions and assess the contributions of newly-acquired constraints on previous models. A sufficiently dense network of gravity observations from previous surveys can extend the impact of newly-acquired bathymetry constraints as they reduce uncertainties in gravity inversions and provide insights into the geological structures controlling ice flow. We use these examples to develop a framework for optimizing future surveys combining gravity and direct measurements.