Evaluation of ESA's Extended Timing Annotation Dataset (ETAD) for Sentinel-1 - First Results for Ice Velocity Monitoring and InSAR Applications in Greenland, Iceland and Norway

SAR images benefit from excellent geometric accuracy due to accurate time measurements in range and precise orbit determination in azimuth. Moreover, the interferometric phase of each single pixel can be exploited to achieve differential range measurements for the reconstruction of topography and the observation of earth surface deformation and surface motions. But these measurements are influenced by the spatial and temporal variability of the atmospheric conditions, by Earth dynamics, and by SAR processor approximations, which may lead to overall displacements shifts of up to several meters. These effects become visible in various SAR applications including the retrieval of ice velocity applying offset tracking and various InSAR applications, which might require several post-processing steps and external information for correction. In this paper we present the Extended Timing Annotation Dataset (ETAD) for Sentinel-1 recently developed in a joint effort by ESA and DLR based on research results and processor prototypes available at DLR.