Glacier surge dynamics of Sortebræ, east Greenland, from synthetic aperture radar feature tracking

We have measured the surface flow rate of the large east Greenland glacier, Sortebræ, through both the initiation and termination of a major surge using synthetic aperture radar (SAR) feature tracking, optimized to minimize error. The Sortebræ surge began between November and January 1992–1993, after at least 6 weeks of subfreezing temperatures over the whole glacier, and propagated rapidly up-glacier from a central nucleus. Sortebræ reached sustained fast flow rates of up to 24 m d−1, and the active phase lasted for 28–32 months before terminating in June 1995. Termination was abrupt, coinciding with the arrival of the spring thaw and the apparent release of a large volume of stored water from a single outlet at the front. The surge mechanism is interpreted as a switch from channelized to distributed drainage, which at present is best explained by Kamb's linked cavity sliding model.