High interannual variability in Greenland seasonal melting from CryoSat-2 altimetry

Abstract:

Changes in the mass of the Greenland Ice Sheet arise owing to an imbalance between ice lost through discharge and the surface mass balance (the net balance between accumulation and ablation processes). Surface mass losses have been the principal driver of Greenland’s recent mass imbalance, owing to an increase in the runoff of surface meltwater as the regional climate has warmed, enhanced in recent summers by changes in atmospheric circulation. Because Greenland surface mass balance follows a strong seasonal cycle with runoff and snowfall confined to summer and winter months, respectively, measurements of the ice sheets elevation change offer a potential opportunity to monitor each process. Here, we use CryoSat-2 satellite altimetry to determine seasonal changes in Greenland ice sheet surface elevation between 2011 and 2019. During this period there has been considerable interannual variability in ice thinning in the summer due to surface melting, which has followed recent changes in atmospheric circulation. At the ice sheet scale, we find our altimeter record of height change within the ablation zone strongly agrees with regional climate model reconstructions of elevation change due to surface processes alone.