Preprint Article Version 1 This version is not peer-reviewed

Using Tandem-X Science Phase Observations to Extract Glacial Topography

Version 1 : Received: 3 October 2018 / Approved: 3 October 2018 / Online: 3 October 2018 (17:21:00 CEST)

A peer-reviewed article of this Preprint also exists.

Hong, S.-H.; Wdowinski, S.; Amelung, F.; Kim, H.-C.; Won, J.-S.; Kim, S.-W. Using TanDEM-X Pursuit Monostatic Observations with a Large Perpendicular Baseline to Extract Glacial Topography. Remote Sens. 2018, 10, 1851. Hong, S.-H.; Wdowinski, S.; Amelung, F.; Kim, H.-C.; Won, J.-S.; Kim, S.-W. Using TanDEM-X Pursuit Monostatic Observations with a Large Perpendicular Baseline to Extract Glacial Topography. Remote Sens. 2018, 10, 1851.

Journal reference: Remote Sens. 2018, 10, 1851
DOI: 10.3390/rs10111851

Abstract

Space-based Interferometric Synthetic Aperture Radar (InSAR) applications have been widely used to monitor the cryosphere over past decades. Because of temporal decorrelation, interferometric coherence often severely degrades on fast moving glaciers. In addition, higher sensitivity ambiguity occurs in large baseline configurations, which are needed for extracting topographic information over low relief areas such as the surface of a glacier. TerraSAR-X add-on for Digital Elevation Measurement (TanDEM-X) observations, which overcome the temporal decorrelation because of their simultaneous measurements by two satellite constellations, have used a short baseline sufficient for generation of excellent digital elevation models in most locations around the world. However, it remains difficult to estimate detailed topographic characteristics over low slope glacier surfaces because of the relatively less sensitive height ambiguity from the small baselines. In this study, we used the TanDEM-X pursuit monostatic mode with large baseline formation following a scientific phase timeline to develop highly sensitive topographic elevation models of the Petermann Glacier of Northwest Greenland. As expected, coherent interferometric phases (> 0.8) were well maintained over the glaciers despite their fast movement thanks to the nearly simultaneous TanDEM‐X measurements. The height ambiguity, which defined as the altitude difference correspondent to phase change of flattened interferogram, of the dataset was 10.63 m, which is favorable for extracting topography in a low relief region. We validated the TanDEM‐X derived glacial topography by comparing it to the SAR/Interferometric radar altimeter observations acquired by CryoSat‐2 and the IceBridge Airborne Topographic Mapper laser altimeter measurements. Both observations showed very good correlation within a few meters of the offsets (‐12.5 – ‐3.1 m) with respect to the derived glacial topography. Because of highly sensitive ambiguity, we could successfully extract detailed geomorphological features on the glaciers. Routine TanDEM-X observations will be very useful to better understand the dynamics of glacial movements and topographic change.

Subject Areas

TanDEM-X; digital elevation model; TanDEM-X Science Phase; radar interferometry; Petermann Glacier; ambiguity height

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