Time-Series Spaceborne InSAR Monitoring of Permafrost Deformation Combined With Backscattering Characteristics: Case Study From the Qinghai–Tibet Engineering Corridor

Global warming and human activities continue to affect the dynamic balance of the Qinghai–Tibet Plateau (QTP) frozen soil environment, affecting the safety and stability of its infrastructure. Spaceborne synthetic aperture radar interferometry (InSAR) is a well-developed Earth observation technology in the last two decades. This study investigated the feasibility of extracting surface deformation in complex and diverse geomorphic landscape regions using ascending–descending orbit combination synthetic aperture radar (SAR) interferometry. The temporal and spatial distribution characteristics of frozen soil deformation and its relationship with climate change were further analyzed. A total of 110 Sentinel-1A ascending and descending SLC images from October 2017 to May 2021 were employed to cover the Qinghai–Tibet engineering corridor. A time-series InSAR (TS-InSAR) method based on a small baseline strategy and backscattering characteristics analysis was developed to estimate the surface deformation in the LOS directions. Then, combined with the geometric parameters of the SAR system, the 2-D deformation results of frozen soil were calculated. Global navigation satellite system (GNSS) data gained from the QHTT Crustal Movement Observation Network of China (CMONOC) reference station was used for validation, demonstrating good agreement in displacement rates and time series. Our study has observed the seasonal components of the GNSS and TS-InSAR results based on a time-series decomposition model. It was revealed that both sets of results are consistent with the existing climate change law, which can reflect the freeze–thaw cycle of frozen soil.