Integration of Sentinel-1 Interferometry and GNSS Networks for Derivation of 3-D Surface Changes

We present a new procedure and program system to integrate Sentinel-1 synthetic aperture radar (SAR) interferometry and Global Navigation Satellite System (GNSS) network observations to estimate 3-D surface changes caused by environmental processes. The procedure is based on the integrated geodetic/geodynamic benchmarks, which are equipped with both ascending (ASC) and descending (DSC) corner reflectors. The results of sparse GNSS observations are interpolated using the ASC and DSC line-of-sight changes provided by the Sentinel-1 mission every six days. The data integration is carried out using a Kalman filter where north, east, and up (vertical) coordinates and their instantaneous velocities are estimated and updated by the GNSS-derived data. The north components are essentially provided by the GNSS observations alone. The procedure was developed and successfully tested on landslide areas in Hungary.