講演情報
[ACC42-04]Evaluating the Capability of InSAR-Derived Surface Deformation to Characterize the Spatio-temporal variability of Active Layer Thickness Dynamics
*Qianhui Liu1、Yonghong Yi1 (1.Tongji University)
キーワード：
Permafrost active layer thickness、InSAR、Seasonal deformation、Pan-Arctic
Accurate assessment of active layer thickness (ALT) dynamics is essential for understanding permafrost evolution and its response to climate change. Interferometric Synthetic Aperture Radar (InSAR) has shown great potential in regional ALT mapping through detecting thaw-induced surface deformation, yet its performance under varying surface and climate conditions remains uncertain. In this study, we assessed the capability of InSAR-derived seasonal deformation to characterize the spatial and temporal variability of ALT in Svalbard based on simulations from an improved Stefan model. The model integrates the snow-insulation mechanism from the Kudryavtsev framework into the traditional Stefan formulation, enabling more realistic characterization of ALT variability in snow-dominated permafrost regions. Validation against in situ observations shows enhanced model performance, with an R of 0.9 and an RMSE of 0.19 m. Across Svalbard, the mean ALT is 1.28 ± 0.47 m, with an average increasing trend of 1.4 ± 0.9 cm/yr. The seasonal deformation in two subregions from 2016 to 2024 was derived using the Sentinel-1 C-band SAR data and the Small Baseline Subset method and evaluated against the simulated ALT. Larger deformation occurs in low-lying, moist, and vegetation-covered surfaces, where sensitivity to ALT variability is highest. By introducing an empirical edaphic factor representing vegetation and moisture conditions, we show that the correspondence between deformation and ALT weakens under drier or sparsely vegetated terrains. Our results demonstrate that the integration of improved analytical ALT modeling and InSAR observations provides new opportunities for large-scale assessment of permafrost active layer changes in a rapidly warming Arctic. Building on the Svalbard case study, the proposed framework is readily transferable to other Arctic permafrost regions, as it relies primarily on globally available reanalysis, snow products, and Sentinel-1 observations. Ongoing work is extending this integrated ALT–InSAR approach to the pan-Arctic domain to enable consistent large-scale assessment of active-layer dynamics under diverse climatic and surface conditions.