Zhang, Yujie and An, Lu and Tang, Leyue and Li, Hongwei and He, Meixi and Li, Rongxing
(2024)
Methods for ice velocity mapping in West Antarctica using historical optical satellite images.
Advances in Polar Science, 35 (2).
pp. 252-263.
Abstract
The Antarctic Ice Sheet harbors more than 90% of the Earth ice mass, with significant losses experienced through dynamic thinning, particularly in West Antarctica. The crucial aspect of investigating ice mass balance in historical periods preceding 1990 hinges on the utilization of ice velocities derived from optical satellite images. We employed declassified satellite images and Landsat images with normalized cross correlation based image matching, adopting an adaptive combination of skills and methods to overcome challenges encountered during the mapping of historical ice velocity in West Antarctica. A basin-wide synthesis velocity map encompassing the coastal regions of most large-scale glaciers and ice shelves in West Antarctica has already been successfully generated. Our results for historical ice velocities cover over 70% of the grounding line in most of the West Antarctic basins. Through adjustments, we uncovered overestimations in ice velocity measurements over an extended period, transforming our ice velocity map into a spatially deterministic, temporally average version. Among all velocity measurements, Thwaites Glacier exhibited a notable spatial variation in the fastest ice flowline and velocity distribution. Overestimation distributions on Thwaites Glacier displayed a clear consistency with the positions of subsequent front calving events, offering insights into the instabilities of ice shelves.
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