Application Of Spaceborne SAR Interferometry And Feature Tracking In Glacier Velocity Monitoring

Antarctica is sensitive to global climate and environment changes, and thus becomes an amplifier and indicator to sense global change. Ice shelves are areas in Antarctica where the most dramatic changes occur, and it is of great sense to monitor surface velocities of ice shelves in conducting research in Antarctic ice sheet mass balance, global climate change, meteorite prediction, and ice avalanche et al. Amery Ice Shelf is the third largest ice shelf in Antarctica. Its horizontal velocity is between 1~4 m per day and it drains about 16% of East Antarctica's ice, which makes it a focus area of domestic and international research.It is a safe, effective, continuous, and economical way to monitor glacier change with multi-temporal remote sensing images. Spaceborne Synthetic Aperture Radar (SAR) becomes an important tool in data acquisition of polar regions by virtue of its all-weather and all-time imaging capacity. The principles and methods of deriving glacier velocities with SAR interferometry and feature tracking are discussed, with the latter one including coherence tracking and intensity tracking, in this paper. One InSAR pair of ERS-1/2 tandem data in local Amery Ice Shelf with one-day time interval is employed as the data source. Ice surface velocities are estimated with methods above and conclusions below are drawn combined with GPS validation data.(1) The estimated average velocity with 2-pass differential interferometry is 0.1m per day, which is inconsistent with the actual situation, indicating that since there are hardly spaceborne InSAR data with 0-baseline and short time-baseline in fast ice flow regions, topographical phase has to be removed with external DEM, and the accuracy of DEM directly determines that of the result.(2) The estimated average velocity with coherence tracking is 1.5 m per day, which is close to GPS validation data. This method has a lower requirement in coherence compared with differential interferometry, and it is very applicable in monitoring the fast incoherent ice flow regions. Its disadvantage is relatively low operation efficiency. Comprehensively considered, however, it is an alternative to differential SAR interferometry in fast ice flow regions.(3) The estimated average velocity with intensity tracking is 1.0 m per day. This method is of high operation efficiency while being of lower accuracy than coherence tracking and its accuracy decreases in featureless ice sheet regions.(4) This study provides certain reference for monitoring glaciers and ice streams in polar regions and mountain areas with spaceborne SAR data.