近25年藏北多年冻土区热喀斯特湖时空动态及热环境响应特征与影响因素OACHSSCD

In the context of global warming,investigating the spatiotemporal dynamics and thermal environment response of thermokarst lakes in the permafrost region of northern Tibet and the influencing factors are crucial for understanding regional hydrothermal processes.Based on 30m resolution Landsat remote-sensing images and ERA5-Land meteorological data from 2000 to 2025,an XGBoost model trained with cross-temporal samples was constructed to identify thermokarst lakes in the permafrost region of northern Tibet,combining spatiotemporal stratified random sampling and cross-validation(independent validation overall accuracy=0.945).Furthermore,an interpretable machine learning framework,XGBoost-SHAP,was employed to quantitatively evaluate the relative contributions of environmental factors to thermokarst lake expansion.The results revealed that:1)Across the study region,the number and area of thermokarst lakes generally increased(by about 53.3％and 52.9％,respectively),with a larger increase after 2015.Within the core change area,thermokarst lake expansion was even more pronounced,with the number of lakes increasing by 98.1％.During this process,the increase in number was dominated by micro and small water bodies,while the area expansion was dominated by medium and large thermokarst lakes.2)Therruiokarst lake expansion exhibited clear spatial clustering.It was mainly concentrated in warm permafrost areas with high ground-ice content and was closely related to ground temperature conditions,ground ice content,and topographic background factors.3)Both the whole region and core change area analyses indicated that lagged land surface temperature(LST_Lagged)and ground ice content(ICE)were important variables explaining thermokarst lake expansion.Under long-term moisture deficit conditions,the thawing of subsurface ice layers may serve as one potential supplementary source for thermokarst lake expansion.