The Extended Timing Annotation Dataset for Sentinel-1—Product Description and First Evaluation Results

This paper introduces the extended timing annotation dataset (ETAD) product for Sentinel-1 (S-1) which was developed in a joint effort of German Aerospace Center (DLR) and European Space Agency (ESA). It allows to correct range azimuth S-1 images geophysical effects as well inaccuracies synthetic aperture radar (SAR) image focusing. In combination with precise orbit solution, these determine absolute geolocation accuracy SAR relative collocation repeat pass stacks. ETAD contains gridded corrections tropospheric ionospheric path delays, tidal-based surface displacements, processing effects, all are computed each data take using standard models from geodesy auxiliary atmospheric data. The helps users significantly improve products better than 0.2 m offers potential solution correcting large scale interferometric phase variations. layout generation described schematically. also reports first results different techniques: first, improvement down few centimeters by verification accurately surveyed corner reflector positions range-azimuth plane; second, well-established offset-tracking technique, that is used systematic ice velocity monitoring sheets glaciers, where can reduce biases sub-centimetric values; third, correction contributions wide-area interferograms national ground motion services. These early proof added value design suited be integrated into flows established applications such ranging targets, speckle/feature tracking interferometry.