Fast and Robust Estimation of Atmospheric Phase Screens Using C-Band Spaceborne SAR and GNSS Calibration

Abstract

AbstractOver the last few years, a growing interest has been observed in the field of Interferometric Synthetic Aperture Radar (InSAR) meteorology. The atmosphere has always been seen as a disturbance in interpreting interferograms (the output product of InSAR processing). A space-borne radar, however, can sense the refractive index of the medium it travels. The refractive index, in turn, is sensitive to pressure, temperature, and humidity of the air. Therefore, SAR data contains information about the atmosphere’s status and can be exploited by Numerical Weather Prediction Models (NWPM) as additional information to improve weather forecasts. This chapter investigates a fast and robust method for generating the so-called Atmospheric Phase Screens (APS) from InSAR data. The method exploits both Permanent Scatterers (PS) and Distributed Scatterers (DS) in an optimal way leading to wide and dense APS maps. When operating at large scales, it is also mandatory to calibrate the data using a network of Global Navigation Satellite System (GNSS) receivers. The calibration can remove the so-called Orbital Phase Screens (OPS) that otherwise severely corrupt the atmospheric measurements. Results using real data acquired by the European Sentinel-1 mission show the potential of InSAR meteorology to provide valuable data to improve weather forecasts.