Influence Of Environmental Factors On The Thickness Of Permafrost Active Layer In Typical Permafrost Regions Of Greater And Lesser Khingan Mountains

With global warming,the permafrost degrades and the thickness of the active layer increases significantly.The degradation process of permafrost is mainly judged by monitoring changes in the thickness of the active layer.The interaction and energy exchange between permafrost and other layers are realized through the freeze-thaw process of the active layer.Therefore,analyzing the thickness variation of the active layer and its driving factors is of great significance for understanding the response of ecosystems in cold regions to global climate change.As a typical high-latitude permafrost region in my country,the Greater and Lesser Khingan Mountains permafrost regions are vulnerable to changes in external environmental factors.In this paper,Wuyiling area and Huzhong area,which are typical permafrost regions of the Greater and Lesser Khingan Mountains,are selected as the research area,and the Stefan equation is used to complete the inversion of the active layer thickness in Wuyiling and Huzhong areas.Geophysical prospecting technology extracts typical environmental factors,and finally uses Structural Equation Modeling(SEM)to explore the factors affecting the thickness change of the active layer.The main conclusions obtained are as follows:(1)This paper carried out field measurements in Wuyiling and Huzhong,and used transient electromagnetic equipment to complete the collection of permafrost thickness data.A total of 31 transects were laid.At 330 sampling points,the thickness data of the active layer was collected using the drilling method.A total of 112 points were collected,and the soil temperature and humidity,longitude and latitude,and elevation data were obtained point by point through the soil temperature and humidity speed tester and GPS toolbox.(2)This paper uses the Stefan equation combined with MODIS surface temperature data to simulate the active layer thickness and spatial distribution inversion at 1 km spatial resolution in the Wuyiling and Huzhong areas,and obtains the spatial distribution map of the active layer thickness.The accuracy of the inversion results is tested by the measured data,which shows that it is feasible to use the Stefan equation to invert the thickness of the permafrost active layer in the Wuyiling and Huzhong areas.(3)Select sampling sites and record data according to the indicated vegetation in the permafrost region.The preliminary analysis results of the thickness change of the active layer are as follows: big different.Moreover,the active layer is thicker in places with more intense human activities,and thinner in places with high vegetation coverage.There is a phenomenon of stratification between permafrost and permafrost at the same measurement site in Huzhong area.The results of SEM analysis show that the soil element has the greatest impact on the thickness of the active layer,and the other elements have little influence on the thickness of the active layer.Neither the results of geographic factors indirectly affecting the thickness of the active layer through NDVI and soil factors nor the results of geographical factors directly affecting the thickness of the active layer were significant.It shows that soil elements are the most important driving factors affecting the thickness of the active layer.Geographical elements and NDVI also have an important relationship with the thickness of the active layer of permafrost,but compared with soil elements,their influence is relatively minor.