CryoSat Estimates of Greenland Elevation Change, 2011-2014, under Varying Surface Melt Conditions.

Abstract:

Two decades of satellite observations have documented substantial mass loss from the Greenland Ice Sheet in response to ocean- and atmospheric-driven melting. During this period, ice mass has fluctuated over a range of timescales, from seasonal cycles in surface melt to decadal and longer responses to the surrounding climate. Mass loss is also highly variable in space, as a result of the distinct geometries and boundary conditions of different glaciological catchments. Resolving changes in ice sheet mass at both a high spatial resolution and temporal sampling frequency is necessary for understanding the timescales and drivers of glaciological change, but has remained a challenge for all satellite geodetic techniques. While radar altimetry has the potential to sample elevation change at a high (~ monthly) temporal frequency and with moderate (~ 5 km) spatial resolution, observations of Greenland Ice Sheet elevation change and mass balance have been challenging because of the kilometer scale resolution of pulse limited elevation measurements and the impact of highly variable snowpack conditions upon the backscattered echo. In this study we investigate the ability of CryoSat to derive estimates of Greenland Ice Sheet elevation change. We use an along-track approach to map ice sheet elevation changes between 2011 and 2014 and evaluate our results using ICEBridge airborne altimetry. Particular attention is given to the influence of changing snowpack conditions on the received echo, and the impact of the extensive 2012 summer melt event on the derived estimates of surface elevation change.