Influences of Snow Cover on the Thermal Regimes of Xing'an Permafrost in Northeast China in 1960s-2010s

The distributive characteristics of snow cover and their impacting mechanisms on ground thermal regimes in Northeast China remain evasive because of limited systematic studies. In this study, based on long-term ground-based observational data and auxiliary topographic data, geographically weighted regression kriging (GWRK) method and the temperature at the top of permafrost (TTOP) model were used to analyze the influences of snow cover duration (SCD) and average snow depth over the SCD (ASDSCD) on the thermal regimes of Xing'an permafrost in Northeast China in the 1960s-2010s. The results show a remarkable reduction of permafrost extent in Northeast China from the 1960s to 2010s, with an average reduction rate of 4.115 x 104 km2/decade. In permafrost regions, from the 1960s to 2010s, average SCD varied between 150 and 160 days, and the regional average of ASDSCD between 8 and 14 cm. Increases in ASDSCD led to a rise of TTOP. From the 1960s to 2010s, the regional average of ASDSCD increased by 3.53 cm, and that of TTOP by 2.02 degrees C. The research results can provide scientific basis and data support for evaluating the responses of permafrost and cold region ecosystems to climate change in Northeast China.