Characteristics And Causes Of Snow Change In Arid Northwest China From 1979 To 2016

As an important and active component of the climate system,snow is very sensitive to climate change and has important implications for the study of global climate change.At the same time,snow is an important freshwater resource to study the effect of snow on water resources.In this paper,the daily datasets of snow depth,and the 0.5°×O.5° monthly precipitation and temperature grid data in China were used to study the snow change in the arid Northwest China during 1979-2016.Mann-Kendall test and other methods were used to calculate the temporal-spatial characteristics of the snow and interpret the reason of the climate change.The results indicated that:(1)From 1979 to 2016,the snow cover in the arid northwestern China is mainly concentrated in winter and spring,and is mainly located in the area near the mountainous area.The depth of snow cover in the Altai Mountains in the northern part of the mountain in spring and winter is almost 10 cm.Compared with the winter and spring seasons,the average snow depth in autumn of 1979-2016 is relatively low,and it is mainly located in Tianshan,northern Altai Mountains,and Kunlun Mountains in the south of southern Xinjiang.During the summer period,there are snow accumulations in only a few areas of Tianshan and Kunlun Mountains.The spatial variation of snow depth and snow cover days in most areas of the arid Northwestern China shows a decreasing trend.The areas where snow depth and snow cover days passed the 0.05 confidence test are mainly concentrated in the southern Xinjiang,western Inner Mongolia and Hexi Corridor,and the Qilian Mountains area.(2)Except for the spring,autumn and winter snow depth,snow cover days,snow cover area in the Qilian Mountains and the winter snow cover days in the Tianshan area show an increasing trend during the period of 1979-2016.The snow area,snow cover days,and snow depth in the areas where snow changes significantly in the spring,autumn and winter tend to decrease.The spatial variation of snow depth and snow cover days in most areas of the arid Northwestern China shows a decreasing trend.The areas where snow depth and snow cover days passed the 0.05 confidence test are mainly concentrated in the southern Xinjiang,western Inner Mongolia and Hexi Corridor,and the Qilian Mountains area.The seasonal cycle changes of snow cover area,snow cover days and snow depth in spring,autumn and winter in the arid Northwestern China mainly focus on the periodic changes of 5 a,10 a,and 19 a.(3)Based on the M-K test,the cumulative anomaly method and the sliding T test,the seasonal changes in the spring,autumn and winter snow cover,snow depth,and snow days in the arid regions of the Northwest China were mainly concentrated in the years 2000 and 1986.Around 2004,the spring,autumn,and winter snow-covered areas,snow days,and the snow-melting year were different in some regions through the three methods,and the mutations did not show good consistency.(4)During the spring,autumn,and winter periods of 1979-2016,the average temperature and precipitation in all regions of the arid regions in northwestern China showed an increasing trend.The number of snow days,snow depth,and snow area in each area showed a negative correlation with the mean temperature and a positive correlation with precipitation.Through the regression analysis of 1979-1979,the northwest arid areas in the spring and autumn winter snow area,the decrease of snow depth and snow days may be mainly caused by the local temperature rise,and the area in the spring and autumn winter snow area,the increase of snow depth and snow days may be mainly caused by the increase of the local precipitation.