Determination of variations in glacier surface movements through high resolution interferometry; Bylot Island, Canada

Interferograms were generated from 10 TerraSAR-X image pairs, with the objective of obtaining estimates of winter surface motion for a slow-moving polythermal arctic glacier. Flow directions were computed using both ascending and descending-pass interferograms for each period, with the median value being adopted as the final direction. The weighted average flow was computed, with weighting based on the inverse of the difference between the ascending and descending-pass displacement estimates for each date. This study uses multiple interferograms with different imaging geometries to provide estimates of down-glacier flow. The methodology adopted minimizes the effects of glacier / satellite track alignment and those resulting from vertical motion of the glacier surface. Current velocities were compared with flow estimates derived from a 1992 ERS-1 image pair. The velocities were similar over most of the glacier, but current velocities were found to be 30% to 50% lower on the lower glacier.