Ice dynamics during a surge of Sortebræ, East Greenland
AbstractSortebræ, a large tidewater-terminating glacier in East Greenland, underwent a major surge between 1992 and 1995 during which the glacier terminus advanced by nearly 10 km. In this paper, intensity tracking, interferometry and visual interpretation have been used to characterize the ice dynamics during the surge from satellite synthetic aperture radar images. The surge had a rapid initiation that saw velocities increase by 60–1500 times, and within 13 months the entire lower 53 km of the glacier was affected. Surge termination occurred very rapidly during summer, and ice velocity dropped from around 20 md–1 to around 2 md–1 in only 3 months. Uniquely, part of the upper glacier remained fast-flowing even after the main surge event had terminated. Ice dynamics together with observations of large turbid lakes at the glacier margins suggest that the surge resulted from a throttling of basal water by a switch in the hydrological system.
