Antarctic Ice Shelf Thickness Change from Multimission Lidar Mapping

by T. C. Sutterley, T. Markus, T. A. Neumann, M. van den Broeke, J. M. van Wessem, and S. R. M. Ligtenberg
The Cryosphere (2019)

Abstract:
We calculate rates of ice thickness change and bottom melt for ice shelves in West Antarctica and the Antarctic Peninsula from a combination of elevation measurements from NASA/CECS Antarctic ice mapping campaigns and NASA Operation IceBridge corrected for oceanic processes from measurements and models, surface velocity measurements from synthetic aperture radar, and high-resolution outputs from regional climate models. The ice thickness change rates are calculated in a Lagrangian reference frame to reduce the effects from advection of sharp vertical features, such as cracks and crevasses, that can saturate Eulerian-derived estimates. We use our method over different ice shelves in Antarctica, which vary in terms of size, repeat coverage from airborne altimetry and dominant processes governing their recent changes. We find that the Larsen-C Ice Shelf is close to steady state over our observation period with spatial variations in ice thickness largely due to the flux divergence of the shelf. Firn and surface processes are responsible for some short-term variability in ice thickness of the Larsen-C Ice Shelf over the time period. The Wilkins Ice Shelf is sensitive to short time-scale coastal and upper-ocean processes, and basal melt is the dominate contributor to the ice thickness change over the period. At the Pine Island Ice Shelf in the critical region near in the grounding zone, we find that ice shelf thinning rates exceed 40 m/yr with the change dominated by strong submarine melting. Regions near the grounding zones of the Dotson and Crosson Ice Shelves are thinning at rates greater than 40 m/yr, also due to intense basal melt. Operation IceBridge provides a validation dataset for floating ice shelves at moderately high resolution when co-registered using Lagrangian methods.