Ice flow in northeast Greenland derived using balance velocities as control

Satellite radar interferometry provides an important new means for measuring ice motion. To make absolute velocity measurements, ground-control points typically are required to refine interferometric baseline estimates. The vast scale and remote location of the ice sheets make it difficult to obtain in situ ground-control data. Balance velocities derived from satellite altimetry digital-elevation models (DEMs) provide an alternate, though less accurate, source of control data. The authors demonstrate a case in which they are able to achieve an accuracy of just over 3 m/yr using this type of control.