南亚高压变化特征及其与我国东部夏季降水的关系

Features of South Asia High’s Variation and Its Relation with the Precipitation of East China in Summer

利用1951~2010年的NCEP/NCAR再分析资料和国家气候中心整编的全国160个测站的6、7、8月降水量资料,客观定义了100 hPa上的南亚高压的面积指数、强度指数和东伸指数。分别研究了南压高压三个特征参数在不同时间尺度上的变化特征,面积指数和东伸指数在50年代至70年代初期呈现减弱趋势,到10年代初期达到最弱,随后迅速增强,并在80年代中期达到最强,此后又迅速将弱,到90年代中期达到平稳。且东伸指数的年代际变化趋势与面积指数一致,表明南亚高压的东西伸展情况与其范围和强度有很大的关系。此外,初步研究了南亚高压与我国东部夏季降水的关系,结果表明,当南亚高压范围扩大,强度增强时,我国东北地区的夏季降水将显著增多,华南地区降水将显著减少。

With the NCEP/NCAR monthly mean reanalysis data from 1951 to 2010 and the precipitation data from June to August deprived from National Climate Centre (NCC), an area index, an intensity index and an east extension index are defined to describe South Asia High (SAH). The area index and the east extension index weakened from 1950s to 1970s, and arrived at their bottom in the beginning of 1970s. In the next years, they kept strengthened to the middle of 1980s, and then weakened quickly to the middle of 1990s. Furthermore, the features of the both indexes’ interannual variation are identical roughly, which show that there exits big relation between the two indexes. In addition, the relation between SAH and the Precipitation of East China in summer is studied. The results show that the precipitation in the northeast area of China would get strengthened when the area index strengths, while the precipitation in the southeast area of China would get weakened.