Spatiotemporal Heterogeneity Of Snow Cover And Causes In China

Snow cover is not only an important part of the climate system,but also the global energy exchange and hydrological cycle.The study of snow cover spatiotemporal variation and heterogeneity is significance to deeply understand the regional climate,hydrology and ecological environment response to climate change.Nowadays,the heterogeneity periodicity and causes of snow cover changes in China are lack of largescale and long-term analysis,and the response mechanism of snow cover to climate change needs to be further explored.Therefore,snow cover changes over China from1951 to 2018 are documented based on an analysis of in situ daily snow depth observations from 730 meteorological stations of China.The main conclusions of this paper are presented in the following paragraph:1)The snow cover in the snow cover areas of China has obvious regional differences,and the snow cover is mainly concentrated in northern Xinjiang,Northeast China and Tibetan Plateau.The snow cover area of Northeast China is characterized by the largest snow-covered days(77 d),while the northern Xinjiang snow cover area is characterized by high average snow depth(8.6 cm).The snow cover area of Tibetan Plateau is characterized by the long snow duration days(168 days),while the annual mean snow depth is the lowest(2.9 cm).2)The snow depth shows an upward trend as a whole,in which the meteorological stations of significant increase are concentrated in the area north of 40 °N,and the Northeast China accounts for the largest proportion.The snow depth in Northeast China and northern Xinjiang shows an upward trend,while that of the Tibetan Plateau shows a downward trend.3)The snow-covered days is increasing,and the significant increase of meteorological stations was concentrated in Northeast China.Regarding the three stable snow areas,the snow-covered days tend to decrease in Tibetan Plateau,while increase in Northeast China and Northern Xinjiang.4)The snow duration days is shortening in China,and 25.2% of the meteorological stations shortened significantly(P < 0.05).The change of snow duration days is the most drastic in Tibetan Plateau,which is shortened by 4 d/10 a.It is caused mainly by the postponement of the snow onset date and the advance of the snow end date.5)Since 1951,various snow indices show obvious short-term and long-term periodic oscillations,and the jump points of snow indices are concentrated around 2000.The snow cover in China has changed more violently since the 21 st century,and the trend is becoming more and more significant.6)The interaction between climatic factors and geographical factors increases the spatiotemporal heterogeneity of snow cover,and the influence of climatic factors is more serious.The increase of temperature has the greatest effect on the snow duration days.This study supplements the deficiency in the study of regional long-time series snow cover change in China,and deeply explores the process,fluctuation and spatiotemporal heterogeneity of snow cover in China.It provides a basis for revealing the mechanism of regional snow cover response to climate change,and has reference value for regional water resources management,disaster prevention and mitigation,and grass ecology.