Antarctic mass budget from 1975-2015 using InSAR, Landsat and RACMO-2

Abstract:

Ice Sheet Mass balance is measured from the difference between the ice discharge along the coast and surface mass balance of the drainage basins of the glaciers. Precise estimation of the mass balance of each glacier needs an exact delineation of their drainage basin, which, ultimately, is defined by the flow of the ice. The precision of mapping is, however, limited by the precision of the actual maps of ice flow, mainly based on speckle tracking, which is not sufficient to fully capture the direction of flow in slow-moving parts of the ice sheets. Here we revisit prior drainage basins of Antarctica using a new precise velocity map based on the interferometric phase by combining InSAR tracks from ALOS/PALSAR-1, ENVISAT/ASAR, ERS-1/-2 and RADARSAT-1/-2. We map ice flow in the interior of the ice sheet at the meter/year level precision. We discuss differences observed between new divides and topographic divides. In addition, we combine this information with a new bed topography from the mass conservation approach and a time history of glacier velocity from Landsat 1975-2015 and InSAR 1992-2015 to calculate the continental discharge since 1975. The results are combined with RACMO2 output products to reconstruct the mass balance of the ice sheet for the past 40 years. The results indicate a significant increase in mass loss from Antarctica starting in the 1990s. This work was performed at UC Irvine and Caltech's Jet Propulsion Laboratory under a contract with NASA.