Observing the near-surface properties of the Greenland ice sheet

Spaceborne radar altimetry over ice sheets has exclusively focused on assessing volume changes through changes in surface elevation. For use in mass balance calculations, these measurements are supplemented with surface property information derived from regional climate models with limited large-scale observational validation. Simultaneously, the strength at which a radar signal is reflected from the surface contains information on these same near-surface properties. Here we show that a quantitative interpretation of European (ESA) CryoSat-2 and French/Indian (CNES/ISRO) SARAL surface echo powers yields timeseries of pan-Greenland wavelength-scale roughness and surface density. Individually, the CryoSat-2 and SARAL results strive toward providing an observational lens to enhance our current understanding of the surface processes affecting ice sheet mass balance and validate their representation by computational models. Taken together, they highlight how diversity in currently operational and future radar satellite altimetry missions can shed light on near-surface vertical heterogeneity.