摘要
利用西藏高原38个气象站自建站以来至2008年的10月至翌年4月逐日积雪资料,依据积雪深度和积雪持续日数两项要素组合的雪灾等级指标,分析了前冬、隆冬和春季3个时段西藏高原不同等级雪灾空间分布。结果表明:主要有3个雪灾发生高频中心区,即以聂拉木为中心的喜马拉雅山脉中段区、以嘉黎为中心的那曲地区中东部区及以错那为中心的喜马拉雅山脉东段区;在时段上雪灾主要出现在前冬和隆冬,春季最少,但在前冬和隆冬雪灾频率分布有较大的空间差异;喜马拉雅山脉中段区、阿里地区、那曲站以中灾和重灾为主。利用NCEP/NCAR再分析月平均高度场数据,对区域性雪灾异常年和无雪灾年进行了合成分析,结果表明:前冬和隆冬北半球500hPa中高纬环流非常相似,自大西洋东海岸向东至西太平有显著的"+-+-"波列,而春季中高纬从欧洲西部为"-+-+-+"波列;3个时段欧洲大陆长波槽脊异常加强,经向环流发展;前冬和隆冬欧亚大陆高度距平场为西高东低,春季正好相反;雪灾年与无雪灾年极涡、乌拉尔山高压脊、贝加尔湖高压脊和北美大槽的强度、位置有较大的差异,而东亚大槽只是春季有所差别外其他时段不明显。
With daily snow cover data collected at 38 meteorological stations in the Tibetan Plateau from Oc- tober through next April during 1960--2008, we analyzed the spatial distribution of three degrees of snow disasters, classified according to snow depth and snow covering days, in pre-winter, winter and spring. Result showed that there were 3 high-frequency centers of the snow disaster： the middle Himalayas area centered in Nielamu, the eastern Naqu area centered in Jiali and the eastern Himalayas area centered in Cuona. The snow disaster mainly occurred in pre-winter and winter with different frequency distribution. The mod- erate snow disaster and severe snow disaster mainly occurred in the middle Himalayas area, All area and Naqu. A synthesis analysis with NCEP/NCAR monthly mean height field reanalysis data in regional snow a- nomaly years and no snow years showed that the 500 hPa atmospheric circulation at high-latitude in the Northern Hemisphere appeared similar in pre-winter and winter with significant ＂-＋- - ＋ -＂ wave train from the Atlantic eastward coast to the western Pacific, and there was a ＂- ＋ - ＋ - ＋＂ wave train from western Europe in the spring. The Long-wave trough and ridge in the European mainland enhanced significantly and the longitude circulation developed in the 3 period. The Eurasia height anomaly fields in pre-winter and win- ter appeared higher in the west and lower in the east, and in spring showed on the contrary. The intensity and position of the Polar vortex, the Ural mountain high pressure ridge, the Baikal Lake high pressure ridge and North American trough have significant that differences between snow disaster years and non-snow dis- aster years. The East Asian trough didn＇t show significant differences except in spring.
出处
《中国沙漠》
CSCD
北大核心
2013年第2期396-402,共7页
Journal of Desert Research
基金
西藏自治区科技厅项目(2008KJAG23)资助
关键词
雪灾
西藏高原
空间分布
大气环流
snow disaster
Tibetan Plateau
spatial distribution
atmospheric circulation
