Examining the effectiveness of tropospheric correction methods on improving InSAR displacement measurements

Abstract

The tropospheric effect is a significant error source in radar observations. To accurately calculate displacement fields, it is essential to apply advanced techniques to mitigate the tropospheric effect in the interferograms. This study examines land subsidence in Tehran province, Iran, using Sentinel-1A data from 2014 to 2021. Methods such as the Generic Atmospheric Correction Online Service (GACOS), ray tracing, and a new integration method were utilized to estimate the tropospheric effect. The integration method and ray tracing technique employed ERA5 reanalysis data from the European Centre for Medium-Range Weather Forecasts (ECMWF). In the final stage, the InSAR interferograms were refined using tropospheric corrections derived from these methods. Comparison of the subsidence data obtained from the three tropospheric correction techniques with Global Positioning System (GPS) observations showed that the results were closely aligned. However, the subsidence velocity derived from the new integration approach proved to be the most accurate.