Validation of alpine glacier velocity measurements using ERS Tandem-Mission SAR data

Five ascending and four descending ERS-1/2 tandem-mode synthetic aperture radar (SAR) interferometry (InSAR) data pairs with useful scene coherence are used to measure the surface flow field of an alpine glacier in the Canadian Rocky Mountains. The topographic component of the interferogram phase is calculated by using a digital elevation model (DEM) 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-ofsight (LOS) measurements are not sufficient to completely resolve the three-dimensional (3-D) surface flow field, several different assumptions for determining the missing variables are considered, and the 3-D surface flow field is estimated by using single and dual LOS measurements. The InSAR results agree with historic and coincident displacement measurements made using traditional point surveying techniques.