摘要
选用陕西86个气象站1961-2007年3~4月降水量和NCEP/NCAR再分析资料,利用标准化降水指数确定陕西春季干旱与多雨的划分指标,并对陕西省春季干旱与多雨年的同期和前期大气环流特征进行了合成分析,结果表明陕西春季降水具有南多北少,年际变率大等特点。陕西春季干旱少雨年同期500 hPa欧亚中高纬度距平场呈＂-＋-＂分布,反映了中亚长波脊强盛,东亚大槽偏深的主要环流特征;而陕西春季多雨年乌拉尔山和日本海为正距平,鄂霍次克海和咸海、里海为负距平,欧亚中、高纬度距平场呈反位相分布,反映乌山阻塞高压建立与崩溃过程中,中亚长波槽经高原东移的环流特征,东亚中纬度纬向环流发展,冷空气易滞留在偏北地区,暖湿气流活跃更易北上,形成了陕西春季多雨天气。从850 hPa流场分布看,陕西春季多（少）雨通常对应同期对流层低层亚洲大陆东岸偏南气流的增强（减弱）。此外前年冬季乌山高压脊偏弱（强）和东亚大槽偏浅（深）与陕西春季多（少）雨有密切联系。
Using the observed precipitation data in March and April from 1961 to 2007 in 86 stations in Shaanxi Province and the NCEP/NCAR reanalysis data,this paper determines the criterion of spring drought and rainy years in Shaanxi Province with the Standard Precipitation Index,and analyses the different atmospheric circulation in spring drought and rainy years in Shaanxi compositely.The results displays that the precipitation in southern part is much than that in northern part of Shaanxi,with significant yearly variations in Shaanxi.During the spring drought years,spring height anomaly distribution in ＂-＋-＂ pattern in mid-high latitudinal of Eurasia at 500 hPa field reveals the atmospheric circulation with intense long-wave ridge in Middle-Asia and stronger trough at East Asia;On the contrary in the spring rainy years height anomaly at 500 hPa field displays opposite distribution,with the negative height anomaly in Okhotsk,Caspian Sea and Aral Sea,while positive height anomaly in Japanese Sea and Ural Mountains.This height anomaly distribution reflects that long-wave troughs move easterly by the Tibetan Plateau with the blocked high sets up and collapses,and the latitude-circulation develops in East Asia,which can easily make cold air accumulated in the northern region,at the same time the active warmer wet air can go northerly,resulting in multiple spring precipitations in Shaanxi.At the 850 hPa stream fields,the rainy（drought） spring years usually mean the stronger（weaker） southerly wind in lower troposphere in the eastern coast of Asian continent.Moreover,there are close relationships between the last winter circulation of weak（intense） high ridge and East Asia trough with the rainy（drought） spring in Shaanxi Province.
出处
《干旱区地理》
CSCD
北大核心
2010年第3期363-369,共7页
Arid Land Geography
基金
国家杰出青年科学基金项目(40825008)
国家科技基础条件平台建设项目(2006DKA32300-03)
黄土与第四纪地质国家重点实验室自主课题(LQ0701)资助
关键词
标准化降水指数
干旱
多雨
环流形势
陕西
standard precipitation index
drought
rainy
circulation
Shaanxi Province
