The ice velocity of the Antarctic ice sheet's outlet glaciers and the areas feeding these glaciers are an important parameter for the quantification of the mass balance of the ice sheet and ice shelves, and for its future development. The break-up or disintegration of such an entire ice shelf like the Larsen Ice Shelf, or the Wilkens Ice Shelf can substantially impact the ice velocity of the glaciers that (used to) feed these ice shelves. A correct quantification of the ice velocity is therefore important also to gain a better knowledge about the future stability of the glacier itself and of the ice sheet areas upstream feeding this glacier.
Ice velocities are derived using Synthetic Aperture Radar (SAR) data. One way is to track speckle in both along (azimuth) and across (range) track directions and by calculation of the two dimensional offsets in amplitude imagery derive the ice velocity. The second approach is to combine the interferometric phases of two independent tracks to retrieve the surface flow vector.
Data from a number of different SAR sensors are used for this dataset: RADARSAT-1 und -2 SAR, Envisat ASAR, ALOS Palsar und ERS1/2 SAR; for version 02 also data from TerraSAR-X, TanDEM-X and Sentinel-1 are used; in order to increase coverage optical imagery from Landsat-8 is used in addition. Coverage in version 02 increased to 99.6% (was 95.1%). Details can be taken from the references down below.
Version 01 of the annual ice velocity data set is based on the same data sets.
The data sets offered here were updated April 24 2017 (version 02) and May 4 2017 (version 1 of annual ice velocity) and downloaded from the NSIDC Data server May 22 2017.