VALIDATION OF ALPINE GLACIER VELOCITY-MEASUREMENTS USING ERS TANDEM-MISSION SAR DATA

Five ascending and four descending ERS-1/2 tandem-mode synthetic apert ure radar (SAR) interferometry (InSAR) data pairs with useful scene co herence are used to measure the surface flow field of an alpine glacie r in the Canadian Rocky Mountains, The topographic component of the in terferogram phase is calculated by using a digital elevation model (DE M) of the terrain and precise orbit data to reconstruct the ERS InSAR imaging geometry. The DEM is derived from the Canada Centre for Remote Sensing (CCRS) Convair-580 airborne SAR interferometer. As dual line- of-sight (LOS) measurements are not sufficient to completely resolve t he three-dimensional (3-D) surface Wow field, several different assump tions for determining the missing variables are considered, and the 3- D surface flow field is estimated by using single and dual LOS measure ments. The InSAR results agree with historic and coincident displaceme nt measurements made using traditional point surveying techniques.