Abstract
Space-based Interferometric Synthetic Aperture Radar (InSAR) applications have been widely used to monitor the cryosphere over past decades. Owing to temporal decorrelation, interferometric coherence often severely degrades on fast moving glaciers. TanDEM-X observations can overcome the temporal decorrelation because of their simultaneous measurements by two satellite constellations. In this study, we used the TanDEM-X pursuit monostatic mode with large baseline formation following a scientific phase timeline to develop highly precise topographic elevation models of the Petermann Glacier of Northwest Greenland. The large baseline provided the advantage of extracting topographic information over low relief areas, such as the surface of a glacier. As expected, coherent interferometric phases (>0.8) were well maintained over the glaciers, despite their fast movement, due to the nearly simultaneous TanDEM-X measurements. The height ambiguity, which was defined as the altitude difference corresponding to a 2π phase change of the flattened interferogram, of the dataset was 10.63 m, which was 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. Routine TanDEM-X observations will be very useful to better understand the dynamics of glacial movements and topographic change.
Highlights
In both Greenland and Antarctica, the significant loss of glaciers plays an important role as a sensitive indicator and modulator of the global climate system interacting with the ocean and atmosphere [1,2,3]
We examined the feasibility of the TanDEM-X pursuit monostatic observation acquired during the TanDEM-X Science Phase to construct high-resolution and highly sensitive topographic elevation models, which could not be achieved using other conventional Interferometric Synthetic Aperture Radar (InSAR) observations
During conventional TanDEM-X SAR interferometric processing under normal operation, the height of ambiguity ranging from 30 m to 45 m might not produce a severe interferometric phase aliasing at a steep slope area, such as a high mountainous area
Summary
In both Greenland and Antarctica, the significant loss of glaciers plays an important role as a sensitive indicator and modulator of the global climate system interacting with the ocean and atmosphere [1,2,3]. Meehl et al (2005) indicated that the sea level would rise by approximately 6 m (m) if Greenland’s ice sheet were to completely melt [7], along with a projected sea level rise of between 0.5 and 1.5 m by 2100 [8,9] Monitoring these rapid changes in polar regions is important to evaluate the vulnerability of the cryosphere, as well as for constraining regional and global climate change models. Reported a rapid change of ice discharge in the Greenland outlet glacier using a satellite-derived surface elevation model [16]. High-resolution DEMs are an essential resource to understand mass balance in ice sheets, the generation of precise DEMS in the cryosphere remains a difficult task. It is impossible to generate a precise DEM of the entire polar region because of costs and access restrictions
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