1979―2014年春季西藏东部雪灾及其大气环流特征

The characters of spring snow disaster and corresponding atmospheric circulation over the eastern Tibet during 1979―2014

利用台站观测积雪厚度等多种气象要素和NOAA大气环流数据,对1979—2014年西藏东部27个台站春季雪灾频次和对应的大气环流异常进行分析。结果表明,西藏东部1979—2014年27站共发生33次雪灾。雪灾主要集中在唐古拉山脉和念青唐古拉山脉之间的地区和山南南部地区;雪灾期间最大积雪厚度越大,总降雪量越多,雪灾平均积雪厚度越大。相对湿度越大,轻灾期间平均积雪厚度越大。风速越大,轻灾和中灾期间平均积雪厚度越大;轻灾和中灾期间,存在从大西洋经高纬度向西太平洋传播的“+-+-+”和“+-+-+-”波列。重灾期间,北大西洋负位势高度场异常强度偏强,存在由大西洋经中纬度向西太平洋传播的“+-+-+-”波列。

Using a variety of in-situ meteorological elements datas such as snow depth and NOAA atmospheric circulation data,the frequency of spring snow disasters at 27 stations in the eastern Tibet and corresponding atmospheric circulation anomalies during 1979―2014 were analyzed.The results showed that there were 33 snowstorms in 27 stations in eastern Tibet during 1979―2014.The snowstorm was mainly concentrated in the area between the Tanggula mountains and the Nyenchenthanglha mountains and the southern part of Shannan;The greater the maximum snow thickness and the total snowfall during the snowstorm,and the greater the average snow thickness of the snowstorm.The greater the relative humidity,the greater the average snow thickness during the light-level disaster.The greater the wind speed,the greater the average snow thickness during the light-level disaster and the middle-level disaster;During the light-level disaster and the middle-level disaster,there were“+-+-+”and“+-+-+-”wave train propagating from the Atlantic to the western Pacific through the high latitude.During the severe-level disaster,the intensity of the North Atlantic negative geopotential height anomalies was stronger than the one during the light-level disaster and the middle-level disaster,and there was a"+-+-+-"wave train propagating from the Atlantic to the western Pacific through the mid-latitude.