Interferometric RADARSAT data are used to map ice motion in the source areas of four West Antarctic ice streams. The data reveal that tributaries, coincident with subglacial valleys, provide a spatially extensive transition between slow inland flow and rapid ice stream flow and that adjacent ice streams draw from shared source regions. Two tributaries flow into the stagnant ice stream C, creating an extensive region that is thickening at an average rate of 0.49 meters per year. This is one of the largest rates of thickening ever reported in Antarctica.

Abstract. Evidence is presented that auroral zone ionospheric disturbances can influence satellite radar interferometry (SRI) obtained with the RADARSAT, ERS and JERS-1 satellites. Fluctuations in ionospheric electron density can lead to an azimuth shift modulation in synthetic aperture radar (SAR) imagery, which can be detected using SRI. Measurements of azimuth shift in SRI can help to differentiate ionospheric from tropospheric propagation problems, and to understand better the impact of the ionosphere on spaceborne SAR. Further, SRI azimuth shift modulation may be useful in mapping patterns of polar auroral zone ionospheric disturbances over large distances.

An interferometric method is used to derive ice motion from RADARSAT data collected during the Antarctic Mapping Mission. Although one cannot solve for both topography and ice motion using one interferometric pair, it is possible to use a coarsely sampled digital terrain model to estimate ice motion using an image registration method. Less accurate than the usual fringe counting method for estimation of radial displacement, the image registration method allows useful motion estimation in both range and azimuth. The method is described and some results shown for a large area (-17,000 km2) including ice flow into the Filchner Ice Shelf.

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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. Index Terms-ERS, glacier, interferometry (InSAR), synthetic aperture radar (SAR).