Exploring Ground Ice Dynamics in central Qinghai-Tibet Plateau Permafrost Region Using SAR interferometry, Landsat and ICESat-2 data

Abstract Climate factors show significant influences on the permafrost dynamics. Numerous studies have delved into the impact of the temperature on permafrost thawing and degradation. However, fewer have focused on the increase in ground ice within permafrost and the contribution of precipitation. In this paper, we integrate the optical remote sensing, InSAR, and ICESat-2 technologies to explore the dynamic change in permafrost ice within Zonag Lake-Salt Lake basin (ZSLB) region. Firstly, a novel method combining InSAR and RobustSTL (robust seasonal trend decomposition algorithm) was proposed to derive long-term deformation and seasonal amplitude of permafrost. Then, cross wavelet transform (XWT) method was utilized to explore the relationship between the deformation and climate factors. After that, the lake areas were extracted through the optical remote sensing images, and the water level of the lake were estimated using the ICESat-2 data. Finally, the volume of increased ground ice in ZSLB is estimated based on the ground deformation derived from InSAR. Our findings indicate that deformation rates in the study area from 2017 to 2021 ranged from −60.7 mm/year to 21.6 mm/year. We observed that permafrost surface uplift is more sensitive to change of precipitation, whereas surface subsidence is more responsive to change of temperature. The rate of change in stored water corresponding to the increase in sub-surface permafrost ice content from 2019 to 2021 is approximately 16.54 × 10 6 m 3 /year, accounting for about 7.1% of the annual average rainfall. This study contributes to a deeper understanding of the permafrost dynamic in the ZSLB and the impact of ground ice changes on hydrological processes.