青藏高原积雪日数与高原季风的关系

Relationship between the Snow Cover Day and Monsoon Index in Tibetan Plateau

利用青藏高原50个气象台站1960-2004年的积雪日数、NCEP/NCAR再分析资料、青藏高原地面加热场强度距平指数和高原季风指数资料,采用EOF、滑动t检验以及相关分析等方法分析了近60年来青藏高原季风的变化特征和近45年来青藏高原积雪日数的变化特征以及二者之间的关系;分析了青藏高原季风与青藏高原高度场和青藏高原地面加热场之间的相关性。结果表明：当初冬（11月）青藏高原地面加热场强度强时,隆冬（12月-1月）的青藏高原冬季风弱,次年春季（4-6月）的青藏高原地面加热场强度弱;当青藏高原夏季风强（弱）时,有利于唐古拉山地区积雪日数的增加（减少）,班戈地区和青海东北部积雪日数的减少（增加）;当青藏高原冬季风强（弱）时,有利于青海北部和西藏南部积雪日数的减少（增加）,喜马拉雅山和唐古拉山积雪日数的增加（减少）。

The basic features and trends of snow cover days over 45 years and the monsoon variations of nearly 60 years,and the further relation between monsoon index and snow cover days in Tibetan Plateau were analyzed using the EOF analysis,the running t-test and correlation analysis methods,snow cover day data（from 1960 to 2004） obtained from 50 weather stations in Tibetan Plateau region,the monthly NCEP/NCAR reanalysis gridded data 2.5°×2.5° from January 1948 to February 2009,the daily mean 600 hPa height reanalysis gridded data 2.5°×2.5° from January 1,1979 to December 31,2009,and the surface heating field intensity data of Tibetan Plateau.The results show that when surface heating field intensity in Tibetan Plateau was strong,the monsoon in midwinter was weak,and the surface heating field intensity was weak in the following spring.The increase（or decrease） of summer monsoon in Tibetan Plateau would result in an increase（or a decrease） of the snow cover days in Tanggula Mountain but a decrease（or an increase） in the Bangoin and north-eastern Qinghai;the increased（or decreased） winter monsoon in Tibetan Plateau would cause an increase（or decrease） of snowcover days in Himalaya mountains and Tanggula Mountain but a decrease（or increase） in the southern Tibet.