Estimation of the Surface Velocity Field of the Aletsch Glacier Using Multi-Baseline Airborne SAR Interferometry

This paper presents a methodology to process airborne interferometric SAR data to measure surface velocity fields of temperate glaciers, and applies it to data acquired over the Aletsch glacier. The first part of the paper deals with the main limitation in airborne interferometric SAR to retrieve reliable interferometric products, namely the existence of the so-called residual motion errors: inaccuracies in the order of a few centimeters in the navigation system. An extended multi-squint approach is proposed for their estimation in the case of non-stationary scenes. The second part of the paper expounds an efficient methodology to derive surface velocity fields with airborne systems, where the line-of-sight displacement is estimated using differential interferometry, and the along-track component by estimating the azimuth coregistration offsets. The necessary steps to finally obtain the 3D surface velocity field are also presented, as well as the possibility to combine different acquisition geometries. Airborne interferometric SAR data acquired by the Experimental SAR system of DLR over the Aletsch glacier, located in the Swiss Alps, are used to evaluate the performance of the proposed approach. The motion of the corner reflectors deployed in the scene is retrieved with an accuracy between 1-5 cm/day using L-band data