青藏高原积雪日数的空间分布及变化分析

Analysis of Spatial Distribution and Change of Snow-Covered Days on the Qinghai-Xizang Plateau

选用青藏高原88个气象台站1961-2007年的逐日积雪观测资料,分析了青藏高原年积雪日数的空间异常分布特征及其时间变化,并对不同季节的积雪日数变化也进行了分析.结果表明:青藏高原年的积雪日数分布在空间上具有很好的一致性,说明高原积雪的多少首先受大尺度环流背景影响的,其次也受海拔和地形及不同天气系统的影响.用REOF方法可将青藏高原积雪日数在空间上分为青海东部型,山南、藏东南型,唐古拉山型,青南高原型、青海柴达木盆地型和西藏西部型6个异常敏感分布型.从空间看,青藏高原的年积雪日数在喜马拉雅山南麓的聂拉木、亚东、错那、改则、申扎以及念青唐古拉山一带呈增多趋势,青南高原、青海海西东部及海东也有明显增加,而拉萨河谷地区、怒江和澜沧江一带及青海海西西部、海北、海南、黄南北部呈减少趋势.

Using the daily snow observation data of 1961--2007 from 88 meteorological stations of the Qinghai-Xizang Plateau, this paper analyses the anomaly spatial distribution of the snow covered days and discusses its variation with time and its seasonal change. The results show that the spatial distribution of snow covered days on the Qinghai-Tibetan Plateau has a very good consistency. The amount of snow on this plateau is influenced primarily by the large scale circulation as the background, and secondly by eleva- tion, topography and different weather systems. Based on REOF, the number of snow covered days of the Qinghai Xizang Plateau is divided into the following six abnormal sensitivity distribution patterns： eastern Qinghai, Shannan Prefecture and southeast Tibet, the Tangula Mountains, Plateau of southern Qinghai, Qaidam Basin and west Tibet. Spatially, annual snow covered days show an increasing trend in Nyalam, Yadong, Cuona, Gaize and Shenzha, which are located in the south of the Himalayas and in the Nyenchen Tanglha mountains, and also on the Plateau of southern Qinghai, east of Haixi and Haidong of Qinghai. In contrast, there is a decreasing trend in the Lhasa valley, the Salween and Lantsang Rivers, west of Haixi, Haibei, Hainan, and the north of Huangnan.