亚欧阻塞高压的变化特征及其与重庆夏季降水的联系

On Variation Characteristics Of Middle-High Latitude Blocking High over Eurasian and Its Relation to Summer Precipitation in Chongqing

使用国家气候中心（NCC）沿用的北半球阻塞高压监测公式，利用NCEP/NCAR逐日500 hPa环流场再分析资料，计算出1961-2011年逐日阻高指数，分析了北半球阻塞高压出现的关键地区阻高指数的年际和年代际变化特征及其与重庆夏季降水的联系。结果表明，三个关键区阻高的季节分布以鄂霍次克海阻高在冬季和夏季出现的频率最高，而春季和秋季则是乌拉尔山阻高活动频繁的季节，贝加尔湖地区阻高活动不及前两个区域活跃。从变化趋势来看，乌拉尔山阻高和鄂霍次克海阻高有增强的趋势，贝加尔湖阻高有减弱的趋势。各关键区的阻高日数都存在2～5年的显著性周期特点。三个关键区对重庆夏季降水的影响各有其特点，贝加尔湖和鄂霍次克海的阻塞形势对重庆夏季降水的影响较大，鄂霍次克海阻高日数对重庆夏季降水的影响比其强度对重庆夏季降水的影响关系更加显著，夏季鄂霍次克海阻高日数偏多（少），重庆夏季降水偏多（少）。

Daily blocking high index has been calculated in this paper over the Northern Hemisphere from 1961-2011 by means of daily NCEP/NCAR height data at 500 hPa .The inter-annual variation and inter-decadal variability of the three key areas and its relation to summer precipitation in Chongqing have also been analyzed .The result shows that ,from the point of seasonal variations ,the Okhotsk blocking high is the highest frequency of occurrence in winter and in summer ,the Ural blocking high is the highest fre-quency of occurrence in spring and in autumn ,and the lowest activity for the Baikal blocking high .Re-cently ,the Ural blocking high and the Okhotsk blocking high appear stronger than normal ,but the Baikal blocking high appears weak climatic background .The blocking days exist obviously cycle characteristics of 2 -5 years .For the blocking high of three key areas and its relation to summer precipitation in Chongqing , each has difference . The Okhotsk blocking days are obvious correlation to summer precipitation in Chongqing ,that are the more （few ） Okhotsk blocking days ,the floods （droughts） for summer precipitati-on in Chongqing .