Glacier Surface Velocity Retrieval Using D-InSAR and Offset Tracking Techniques Applied to Ascending and Descending Passes of Sentinel-1 Data for Southern Ellesmere Ice Caps, Canadian Arctic
Glacier Surface Velocity Retrieval Using D-InSAR and Offset Tracking Techniques Applied to Ascending and Descending Passes of Sentinel-1 Data for Southern Ellesmere Ice Caps, Canadian Arctic
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DOI：
10.3390/rs9050442
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发表时间：
2017-05-01
期刊：
影响因子：
5
通讯作者：
Navarro, Francisco J.
中科院分区：
文献类型：
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作者：
Sanchez-Gamez, Pablo;Navarro, Francisco J.
Sentinel-1任务的逐级扫描地形观测（TOPS）采集模式提供了广泛的覆盖范围，每次采集的分辨率为5分钟距离和20米方位角，这使得这种采集模式对冰川速度监测具有吸引力。在这里，我们使用偏移跟踪和差分干涉合成孔径雷达（D-InSAR）技术，结合上升和下降通道，从南埃尔斯米尔岛冰盖（加拿大北极）检索地表速度。我们通过省略方位角偏移来优化偏移跟踪技术。通过这样做，我们能够提高速度乘积的最终分辨率，因为Sentinel-1在方位角方向上的分辨率较低。同时，我们避免了在数据中表现为方位角条纹的不希望的电离层效应。D-InSAR技术适用于慢动区域，而偏移跟踪更适用于快动区域。这项研究表明，这里使用的方法是互补的，使用两种方法来确定冰川速度比只使用其中一种要好。我们观测到最快的潮汐冰川的表面速度可达1200米年（-1）。终止陆地的冰川显示出典型的速度在12至33米/年（-1）之间，尽管在封闭山谷的狭窄地带，峰值可达150米/年（-1）。
The Terrain Observation by Progressive Scans (TOPS) acquisition mode of the Sentinel-1 mission provides a wide coverage per acquisition with resolutions of 5min range and 20m in azimuth, which makes this acquisition mode attractive for glacier velocity monitoring. Here, we retrieve surface velocities from the southern Ellesmere Island ice caps (Canadian Arctic) using both offset tracking and Differential Interferometric Synthetic Aperture Radar (D-InSAR) techniques and combining ascending and descending passes. We optimise the offset tracking technique by omitting the azimuth offsets. By doing so, we are able to improve the final resolution of the velocity product, as Sentinel-1 shows a lower resolution in the azimuth direction. Simultaneously, we avoid the undesired ionospheric effect manifested in the data as azimuth streaks. The D-InSAR technique shows its merits when applied to slow-moving areas, while offset tracking is more suitable for fast-moving areas. This research shows that the methods used here are complementary and the use of both to determine glacier velocities is better than only using one or the other. We observe glacier surface velocities of up to 1200 m year(-1) for the fastest tidewater glaciers. The land-terminating glaciers show typical velocities between 12 and 33 m year(-1), though with peaks up to 150 m year(-1) in narrowing zones of the confining valleys.