Improved SBAS-INSAR Based on Two-Stage Optimal Interferometric Pair Selection for Permafrost Monitoring in the Qinghai-Tibet Plateau

Small-Baseline Interferometric Synthetic Aperture Radar (SBAS-InSAR) has been widely used in the field of permafrost deformation monitoring. However, previous research has mainly relied on short-term interferograms, which may cause phase bias or signal fading. In this study, we propose an improved SBAS-InSAR algorithm based on a two-stage optimal interferometric pair selection strategy that integrates both short-term and long-term interferograms. The central Qing-Tibet Plateau, characterized by its high elevation and low vegetation cover, provides an ideal region for permafrost monitoring using InSAR technology. By comparing the results of the SBAS-InSAR technique based on three different interferogram networks, our method can detect 129 additional thawing permafrost areas with local subsidence in the QTP study areas. In contrast, these subsidence areas are missed by SBAS-InSAR based on two other interferogram networks.