北半球夏季副热带西风急流变异及其对东亚夏季风气 候异常的影响

探讨了东亚地区副热带西风急流(EAJS)位置的年际 变化特征、影响及其可能机制. EAJS南北变动的影响主要集中在亚澳季风区和气候平均的北 半球副热带西风急流轴的南北两侧,这与SOI或ENSO相联系的大气环流响应很不相同,后者的 影响主要表现在中、东太平洋上. 北半球副热带西风急流存在着两个显著不同的模态,其中 一个模态反映的是亚太尤其是东亚地区的西风急流的南北变异,另一个模态出现在150°E～1 20°W的中、东太平洋上. 它们分别联系着不同的太平洋海温异常分布,但都能对夏季200hPa 南亚高压的强度产生影响,尤其是南亚高压的东部,从而可以对我国东部夏季旱涝灾害的形成 产生作用.

Anomalies of the extratropical west erly Jet in the north hemisphere and their impacts on east Asian summer monsoon climate anomalies

〓We study the interannual variability of th e extratropical westerly jet over East Asian (EAJS), its impacts and possible me chanisms. The impact of south north alternation of EAJS concentrates in the Asi an Australian monsoon region and the two sides of the climatological position o f EAJS, which is quite different from the atmospheric responsible of SOI(South Oscillation Index) or ENSO(El Nino South Oscillation). The impacts of the latte r exhibit mainly in the middle and east Pacific. There exist two dominant modes of the summer subtropical westerly jet in the north hemisphere. The first deals with the south north alternation of the westerly jet in the Asia Pacific area, especially in the East Asia. The second mode appears in the mid east Pacific o f 150°E～120°W. The two modes link with two significantly different SST patter ns in the Pacific, but they can all influence the intensity of 200 hPa South Asi an Anticyclone, especially the intensity of the east part of the South Asian Ant icyclone, and which will contribute to the formation of summer floods and drough ts in eastern China.