A Baseline-Combination Method for Precise Estimation of Ice Motion in Antarctica

Differential synthetic aperture radar interferometry (D-InSAR) is a powerful method for measuring surface deformation, such as in studies of the earthquake cycle, volcano deformation monitoring, land subsidence monitoring, and glaciological studies. However, its application to glaciological studies is limited by the lack of accurate digital elevation models (DEMs), particularly over the Antarctic ice sheet. Previous studies on ice motion using D-InSAR are mostly based on short-baseline interferograms because these data sets are insensitive to DEM errors. Unfortunately, short-baseline interferograms are often unavailable. In this paper, we refine the InSAR technique by using a combination of two interferograms to make accurate ice-flow velocity measurements. The refined technique is tested in the Grove Mountains area, East Antarctica. Ice-flow velocities from the baseline-combination method are in good agreement with those measured by short-baseline interferograms. This method is also capable of reducing phase errors by combining the appropriate data sets. The reliability of the data sets is assessed by defining a baseline-combination parameter and ensuring that it is less than or equal to 1.0. With this method, we are able to extend the usefulness of D-InSAR for glaciological studies.