Climate warming makes permafrost on the Qinghai-Tibet Plateau (QTP) undergo considerable thawing and degradation. Ground deformation is a crucial indicator of permafrost degradation. This can be measured through the latest multi-temporal Interferometric Synthetic Aperture Radar (InSAR) methods.
But as a result of the powerful heterogeneity of freeze-thaw processes, the patterns and magnitudes of large-scale ground deformation on QTP are not quantified much or understood.
Scientists from the Northwest Institute of Eco-Environment and Resources of the Chinese Academy of Sciences (CAS) have come up with a Moderate Resolution Imaging Spectroradiometer (MODIS)-Land-Surface-Temperature-Integrated InSAR method to rebuild the permafrost-related ground deformation. Furthermore, they noted extensive seasonal and long-term ground deformation on the central QTP.
Through geophysical detector and spatial analysis, the scientists discovered that terrain slope is the primary factor regulating seasonal deformation. Powerful magnitudes and alterations of seasonal deformation are most pronounced in flat or gentle-slope regions as a result of the high water capacity.
Besides, the scientists note that linear subsidence is greater in the regions with high ground ice content and warm permafrost. Such findings show that under constant warming, the transition from cold permafrost to warm permafrost might result in highly extensive ground ice loss.
This study illustrates the ability of the permafrost-tailored InSAR methods to measure the magnitudes and spatial variations of the freeze-thaw processes and the melting of ground ice under various surface conditions (like vegetation types, different terrains, ice-poor, or ice-rich permafrost) at a high resolution over a large scale.
In the inaccessible or remote permafrost regions on QTP or in the Arctic, this study offers practical permafrost-tailored InSAR techniques and plans to map and measure the freeze-thaw processes and the degradation of permafrost more than on large scales. This is useful for comprehending the permafrost reaction to local disturbance and climate warming.
Chen, J., et al. (2021) Magnitudes and patterns of large-scale permafrost ground deformation revealed by Sentinel-1 InSAR on the central Qinghai-Tibet Plateau. Remote Sensing of Environment. doi.org/10.1016/j.rse.2021.112778.