Ice sheet wide comparison of coincident laser and radar observations from ICESat-2 and CryoSat-2 for Greenland and Antarctica

Radar altimetry has since the early 1990s provided the scientific community with key observations about the changes of the Earth's ice sheets and glaciers. This long-term record is of vital importance for understanding current and future trends in ice loss, and the processes governing the ice sheets contribution to global sea-level rise due to a warming climate. Though modern radar altimetry allows for detailed mapping of the changes in mass of the ice sheets, this measurement is still affected by changes in the radar scattering regime at the snow-air interface, manifested by penetration of the radar signal into the firn column. These regime changes can introduce biases in the retrieved elevation change signal, which to date are difficult to quantify due to lack of an adequate model for correcting changes in the scattering regime and large-scale validation datasets. With the launch of ICESat-2 in September, 2019, we have the opportunity of comparing unbiased laser measurements with overlapping radar data from CryoSat-2, in a similar way to ICESat vs. Envisat. This temporal overlap between missions allows us to investigate a range of different issues ranging from laser-radar penetration biases to changes in snow properties, spatially and temporally for both ice sheets. Quantifying and modelling these effects is essential for the accurate reconstruction of the long-term trends in ice-sheet mass derived from the satellite altimetry record, which will improve projections of sea-level change.

This work was performed at the Jet Propulsion Laboratory (JPL), California Institute of Technology, under a contract with the National Aeronautics and Space Administration and supported by the NASA Cryosphere Science program © California Institute of Technology. Government Sponsorship acknowledged.