Analysis on the Variation of Snow Cover in the South of Huangnan in the Last 56 Years

Selected in the southeastern Qinghai Huangnan region 2 meteorological stations 1960 ~ 2015 monthly snow data,using the mathematical statistics and the method of linear regression analysis of trends in the snow,of Southern Huangnan yearly snow days and the maximum snow depth change characteristics of diagnosis.Resultsshow that: 1) Southern Huangnan snow day number increased,the increase rate for 0.152/a.2) maximum snow depth in spring and winter is weakly increasing trend,autumn decreased slightly,the overall trend of weakly decreased. 3) Huangnan region of snow days and the maximum snow depth is significant correlation,snow is usually deeper snow days longer. 4) annual,quarterly and monthly number of snow cover days occurred from less to more mutations that occurred in spring in 1965,autumn in 1973,winter in 1974 mutations,the mutation years occurred in 1970. 5) by wavelet analysis,the last 56 years,the number of snow days in the southern region of Huangnan is more obvious than the 6 year period,there is a quasi 3A oscillation period in the end of 60 ~ 70 s,and other periodic signal intensity is weak.