INTERFEROMETRIC ESTIMATION OF 3-DIMENSIONAL ICE-FLOW USING ASCENDING AND DESCENDING PASSES

Satellite radar interferometry (SRI) provides an important new tool fo r determining ice-flow velocity, Interferometric measurements made fro m a single-track direction are sensitive only to a single component of the three-component velocity vector, Observations from along three di fferent track directions would allow the full velocity vector to be de termined, A north/south-looking synthetic aperture radar (SAR) could p rovide these observations over large portions of the globe, but not ov er large areas of the polar ice sheets, We develop and demonstrate a t echnique that allows the three-component velocity vector to be estimat ed from data acquired along two track directions (ascending and descen ding) under a surface-parallel how assumption, This technique requires that we have accurate estimates of the surface slope, which we also d etermined interferometrically, To demonstrate the technique, we estima te the three-component velocity field for the Ryder Glacier, Greenland , Our results are promising, although we do not have yet ground-truth data with which to determine the accuracy of our estimates.