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A digital representation of ice surface velocity is essential for a variety of glaciological, geologic and geophysical analyses and modeling. Here, we present a new, reference, comprehensive, high‐resolution, digital mosaic of ice motion in Greenland assembled from satellite radar interferometry data acquired during the International Polar Year 2008 to 2009 by the Envisat Advanced Synthetic‐Aperture Radar (ASAR), the Advanced Land Observation System (ALOS)'s Phase‐Array L‐band SAR (PALSAR) and the RADARSAT‐1 SAR that covers 99% of the ice sheet in area. The best mapping performance is obtained using ALOS PALSAR data due to higher levels of temporal coherence at the L‐band frequency; but C‐band frequency SAR data are less affected by the ionosphere. The ice motion map reveals various flow regimes, ranging from patterned enhanced flow into a few large glaciers in the cold, low precipitation areas of north Greenland; to diffuse, enhanced flow into numerous, narrow, fast‐moving glaciers in the warmer, high precipitation sectors of northwest and southeast Greenland. We find that the 100 fastest glaciers ( v > 800 m/yr) drain 66% of the ice sheet in area, marine‐terminating glaciers drain 88% of Greenland, and basal‐sliding motion dominates internal deformation over more than 50% of the ice sheet. This view of ice sheet motion provides significant new constraints on ice flow modeling.
Rignot et al. (Tue,) studied this question.