Interferometric analysis of the deformation pattern of the northern Larsen Ice Shelf, Antarctic Peninsula, compared to field measurements and numerical modeling

The motion field of the northern Larsen Ice Shelf, Antarctic Peninsula, was analyzed using radar interferometry in combination with field measurements and finite-element model calculations. The ice shelf between Jason Peninsula and Seal Nunataks has been in steady retreat since January 1995. Model calculations suggest that the ice shelf is in a stage of irreversible retreat since the last calving events in summer 1998/99. The interferometric analysis is based on synthetic-aperture radar data of the tandem mission of European remote-sensing satellites ERS-1and -2 in austral spring 1995. The phase contributions due to tidal motion were estimated from the vertical displacement at those parts of the grounding zone where the horizontal motion is close to zero, in order to separate the vertical and horizontal motion components over the ice shelf. Satellite-derived velocities compare well with the long-term field measurements along a transverse and a longitudinal profile. The real interferograms and synthetic interferograms, calculated from model velocities, show reasonable agreement over the main parts of the ice shelf, but differ in the boundary zones where the details are not resolved by the model.