Using TanDEM-X Pursuit Monostatic Observations with a Large Perpendicular Baseline to Extract Glacial Topography

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.

Relationship between Lidar-Derived Canopy Densities and the Scattering Phase Center of High-Resolution TanDEM-X Data

“…Another important factor to consider is the relative height accuracy of the DEM, which is specified as 2 m for flat terrain (slopes < 20°) and 4 m for mountainous regions (slopes > 20°) [62,63,86,87]. Regarding the interpretation of the data, this allows for some margin of error, as the accuracy of the InSAR Height measurements is strongly influenced by the relative height accuracy of the TanDEM-X data.…”

Special Issue on Selected Papers from the “International Symposium on Remote Sensing 2018”

“…Hong et al [10], in their paper entitled "Using TanDEM-X Pursuit Monostatic Observations with a Large Perpendicular Baseline to Extract Glacial Topography", performed a feasibility test to construct high-resolution and high-precision topographic elevation models from TanDEM-X pursuit monostatic observations during the TanDEM-X Science Phase. For this study, the authors evaluated the measurement performance from more detailed topographic height variations along the moving surfaces of low slopes like glaciers.…”

A Modified Approach of Extracting Landfast Ice Edge Based on Sentinel-1A InSAR Coherence Image in the Gulf of Bothnia

“…In the 1990s, Dammert et al [23] demonstrated that InSAR technology has great value and potential in studying the backscattering characteristics of fast ice and sea ice mechanics models. In later studies, InSAR was successfully used to obtain sea ice motion maps in the Antarctic and develop highly precise topographic elevation models of glaciers [24,25]. InSAR has also provided information pertaining to landfast ice topography [14,16].…”