Analysis Of Spatiotemporal Variation Of Snow Depth And Its Influencing Factors On The Qinghai-Tibet Platea

As the region with the largest snow cover in the Northern Hemisphere,the Tibetan Plateau has significant impacts on climate,hydrogeology,and ecological environment due to changes in snow cover.Therefore,it is of great significance to study the spatiotemporal variation characteristics and influencing factors of snow cover depth in the Tibetan Plateau.Based on the station and 0.05°high-resolution snow depth data,this paper uses a variety of mathematical statistics methods to analyze the temporal and spatial variation characteristics of snow depth in the Tibetan Plateau,such as interdecadal variation,periodic variation,sudden change year,spatial distribution and trend change,and center of gravity change,Further exploration was conducted on the driving factors of snow depth changes in the Tibetan Plateau region.The main conclusions of this study are as follows:(1)The snow depth on the Tibetan Plateau showed an overall trend of first increasing and then decreasing between 1961 and 2012,with a significant increase in the 1970s and 1980s and a decrease starting from the mid-1990s.The snow depth in the western region of the Tibetan Plateau varies periodically from 13 to 17 years,while in the eastern region it varies periodically from 3 to 7 years.The sudden change in snow depth from less snow period to more snow period mainly occurred in the mid-1960s to early 1970s,and the sudden change from more snow period to less snow period mainly occurred in the late 1990s to early 21st century.(2)The annual and spring-autumn-winter snow depth distributions are relatively similar during 2001-2017,where the high value areas of snow depth are mainly located in several high mountain ranges(Karakorum,Himalayas,Bayan Har,and Nianqing Tanggula),and the low value areas are mainly distributed in Qiangtang Plateau and Qaidam Basin.The snow depth reduction area is mainly located in the western Qiangtang Plateau,with the largest decrease trend of-1.02cm/a in winter,while the increase area is mainly located in the Karakoram Mountains in the northwest,the the Himalayas Mountains in the southwest and the eastern mountain areas,with the largest increase trend of 0.92cm/a in autumn.(3)The decrease in surface solar radiation was the main factor for the increase in snow depth in the 1970s and 1980s on the plateau,and the two were significantly negatively correlated;the significant increase in temperature in the mid-to-late 1990s was the main factor for the decrease in snow depth,and the two were significantly negatively correlated;precipitation was positively correlated with snow depth overall.(4)The degree of contribution of surface solar radiation,temperature and precipitation to snow depth in four seasons during 2001-2017 is:autumn>winter>spring>summer,and the contribution to the eastern and southwestern regions of the plateau is greater in autumn.The center of gravity of snow depth on the Tibetan Plateau gradually shifts northward in spring,autumn and winter,and surface solar radiation and temperature mainly have a significant negative correlation with the latitudinal change of the center of gravity of snow depth in autumn,while precipitation mainly has a significant positive correlation with the latitudinal change of the center of gravity of snow depth in autumn.(5)Everest station is mainly influenced by westerly winds during the non-monsoon period,with most of the air masses coming from the west and northwest,and by southerly winds during the monsoon period,with air masses mainly coming from the Arabian Sea and the Bay of Bengal,and the black carbon generally shows a concentration change of pre-monsoon>winter>post-monsoon>monsoon.During the monsoon period,the atmospheric black carbon concentration has less influence on the snow depth,and during the non-monsoon period,the black carbon concentration and snow depth both show negative correlation,among which the winter and pre-monsoon periods show significant negative correlation,and the snow depth is larger when the atmospheric black carbon concentration is below 300 ng/m~3,and less when the atmospheric black carbon concentration is above 800 ng/m~3.