On The Exploitation of Etad Data for the Atmospheric Phase Screen Filtering of Medium/High Resolution Dinsar Products

The Extended Timing Annotation Dataset (ETAD) product provides azimuth and range timing corrections to improve the geometric accuracy of Sentinel-1 (S-1) Synthetic Aperture Radar (SAR) images. Moreover, the product also contains dedicated layers for mitigating atmospheric path delays, estimated by using Numerical Weather Prediction (NWP) models. In this paper, we present an analysis on the exploitation of the ETAD correction layers for the removal of the Atmospheric Phase Screen (APS) signals from Differential Synthetic Aperture Radar (DInSAR) interferograms generated at medium/high spatial resolution. The performed analysis, involving a dataset acquired over the Napoli bay area, highlighted that the computed ETAD APS corrections introduces several artefacts in the corrected interferograms. In particular, these artefacts are more evident where a relevant topography gradient is present, because they are caused by the ETAD DEM height variations due to the different projections within the specific range-azimuth grid of each S-1 burst image. A simple solution to remove the above mentioned artefacts is also presented, together with some results confirming the validity of this method.