印度季风与东亚夏季环流的遥相关关系

THE TELECONNECTION RELATIONSHIP BETWEEN INDIAN MONSOON AND EAST ASIAN SUMMER CIRCULATION

通过NCAR/NCEP再分析资料诊断发现印度夏季降水与东亚 5 0 0hPa位势高度有显著的相关性 ,形成了印度—东亚遥相关型 (IEA型 )。结合太平洋日本型 (PJ型 )的特征 ,指出PJ型主要决定夏季西北太平洋副热带高压的南北位置 ;IEA型在一定程度上影响副高脊西伸的东西经度或夏季中国大陆上空的平均位势高度距平。气候模式数值试验揭示出印度—东亚遥相关型对东亚很重要并且与印度洋海温异常有关 ,借此提出ENSO影响东亚夏季风的两条途径 :一条是直接路径 ,另一条为选择性路径。

This paper aims at the relationship between the Indian monsoon and the summer circulation of the East Asia. The diagnostic study reveals a significant correlation between the Indian summer rainfall and the 500 hPa heights over the East Asia, based on NCAR/NCEP reanalysis data sets. The correlation structure seems to be an implicit teleconnection pattern, named as Indian-East-Asian (IEA) pattern, because of no significant correlation between the rainfall and the 500 hPa height above India around. The spatial structure of the IEA pattern implies its important influence on the departures of the 500 hPa height over the East Asia, which exerts impact on the zonal location of the subtropical high in northwestern Pacific while the Pacific-Japan (PJ) pattern affects its meridianal location, as well known. The numerical experiments for a case of 1982 show that the IEA pattern is a key chain that makes the East Asian summer monsoon and South Asian monsoon connected. Notice the tie of the ENSO and Indian monsoon, we introduce two ways by which the ENSO affects the East Asian summer monsoon. They are a direct way: ENSO → PJ Pattern → East Asian summer monsoon,and a selective way:ENSO → south Asian monsoon → IEA pattern → East Asian summer monsoon.