Profile of the Greenland ice sheet acquired by CryoSat-2. The profile shows an estimate of ice-sheet elevation and variability of surface characteristics (colour-coded returned echo power levels) across a 2500 km transect from south to north.
CryoSat is able to measure the freeboard (the height protruding above the water) of floating sea ice with its sensitive altimeter. From the freeboard, the ice thickness can be estimated.