This MEaSUREs Ice Velocity (Antarctica) layer provides a high-resolution digital mosaic composite of ice motion in Antarctica assembled from multiple satellite interferometric synthetic-aperture radar systems: RADARSAT-1, ERS-1 and 2, ALOS PALSAR, ENVISAT ASAR, RADARSAT-2.

An ice sheet is a mass of glacial land ice extending more than 50,000 square kilometers (20,000 square miles) and forms in areas where snow that falls in winter does not melt entirely over the summer. Over thousands of years, the layers of snow pile up into thick masses of ice, growing thicker and denser as the weight of new snow and ice layers compresses the older layers. Ice sheets are constantly in motion, slowly flowing downhill under their own weight. Near the coast, most of the ice moves through relatively fast-moving outlets called ice streams, glaciers, and ice shelves. Within the image, the various colors, ranging from dark blue (0 m/y) to dark red (5600 m/y), indicate the velocity of the various ice outlets.

The MEaSUREs Ice Velocity (Antarctica) layer’s sensor and imagery resolution is 450 m, and the temporal resolution is 15 years.

References: MEaSUREs InSAR-Based Antarctica Ice Velocity Map, Version 1 (NSIDC-0484); NSIDC Quick Facts on Ice Sheets