Mitigating Elevation-Dependent Errors in Tropospheric Delay Interpolation for InSAR Applications

Abstract. Interferometric Synthetic Aperture Radar (InSAR) is a powerful tool for detecting ground deformation with millimeter precision. However, atmospheric effects, particularly tropospheric delays, significantly degrade the accuracy of InSAR-derived measurements. This study investigates elevation-dependent errors in tropospheric delay interpolation using Global Navigation Satellite System (GNSS)-derived Zenith Tropospheric Delay (ZTD) data. Two GNSS networks with similar spatial configurations but different elevation characteristics were analyzed to quantify the effect of altitude differences on interpolation accuracy. A novel correction method was proposed to mitigate the elevation-induced bias by isolating and modifying the dry component of the ZTD using the Saastamoinen model. Results demonstrate that this approach substantially improves interpolation accuracy up to 92% enhancement in high-relief areas. The findings highlight the critical importance of considering elevation effects when integrating GNSS and InSAR data for atmospheric delay correction, especially in mountainous regions.