Combined use of InSAR and GLAS data to produce an accurate DEM of the Antarctic ice sheet: Example from the Breivika–Asuka station area

Surface elevation data for the Breivika–Asuka Station area, East Dronning Maud Land, Antarctica, obtained during ground surveys undertaken in 1987 were compared with elevation data measured by the Geoscience Laser Altimeter System (GLAS) onboard the Ice, Cloud, and land Elevation Satellite (ICESat) in 2003. The two sets of measurements were consistent within ±12.4 m for an elevation range from 300 to 1000 m. We produced an interferometric synthetic aperture radar (InSAR) digital elevation model (DEM) with 50 m grid spacing and InSAR DEM heights were corrected using GLAS heights as ground-truth data. The height differences are assumed to have a quadratic function of rectangular polar stereographic coordinates with six coefficients, and the most probable estimate of the correction parameter set was calculated using a least squares method. Before correction, the root-mean-square (rms) height error was ±284 m; after correction, the associated error was reduced to ±22.3 m, where the absolute error in the horizontal coordinates (grids) was ±230 m. The resultant InSAR DEM height error is twice as large as the GLAS DEM height error; however, the accuracy of the resultant InSAR DEM is reasonable when we consider the limitations of single baseline InSAR and the steep slopes (range in elevation: 1000 m) within the ice sheet region. An InSAR DEM with high spatial resolution and 2 m relative accuracy in terms of yearly change is useful for monitoring ice volume (mass) change by a superconducting gravimeter.