ICE FLOW DYNAMICS OF THE GREENLAND ICE-SHEET FROM SAR INTERFEROMETRY

Synthetic-aperture radar (SAR) interferograms produced from ESA's ERS- 1 satellite, provide the first synoptic view of ice flow dynamics of t he western sector of the Greenland Ice Sheet. Glacial motion is detect ed in the radar ranging direction at millimetric scales, across a comp lete sequence of snow accumulation and melting regimes, despite signif icant variations in their radar scattering properties. Ice flow evolve s from a slow, regular motion at the higher elevations. At lower eleva tions, motion is strongly convoluted by meter-scale undulations in sur face topography, which have a unique interferometric signature that en ables a novel approach for retrieving flow direction. Inferred flow di rections, combined with surface displacements in the radar ranging dir ection, yield ice velocity estimates that are within 6% of in-situ mea surements gathered along a 40 km survey line. Application of repeat-pa ss SAR interferometry to the entire Greenland Ice Sheet should enable precise mapping of its ice flow dynamics at an unprecedented level of spatial detail.