东亚夏季风与ENSO、IOD间联系的特征分析

Analysis of the Relationship between East Asian Summer Monsoon and ENSO, IOD

摘要: 采用印度洋偶极子指数(DMI、TIOD)、Nino3指数和3类东亚夏季风指数，比较和分析印度洋偶极子、ENSO (El-Niño-Southern Oscillation)与东亚夏季风间联系的特征。结果显示：1) 不同的类型东亚夏季风指数与不同的海温模态指数相关性不同，如：用风场定义的Iljp指数反映印度洋IOD (Indian Ocean Dipole)影响的能力就比用海陆海平面气压定义的Isn要强。2) 同一东亚夏季风指数分别与DMI、Nino3指数的联系都呈明显的年代际变化特征，IOD和ENSO对夏季风的影响是相反的。东亚夏季风指数在20世纪90年代之前与DMI都呈现着明显的正相关关系。而从20世纪90年代后期开始当季风指数与IOD指数开始表现为负相关。其与Nino3指数则呈现相反的相关状态。同时东亚夏季风与IOD、ENSO年际变化之间的联系都具有此弱彼强的特点。3) 从空间上来看，不同的东亚夏季风指数受到印度洋、太平洋海温影响的程度不同，其季风在偏强、偏弱年对应的海温模态也不完全一致。在季风偏强年对应太平洋上都出现ENSO正相位，赤道印度洋上海温整体偏冷。在季风偏弱年三个指数对应的太平洋海温模态各不相同，赤道印度洋整体偏暖。

Abstract: This paper uses the Indian Ocean Dipole Index (DMI, TIOD), the Nino3 index and the three East Asian summer monsoon indexes to compare and analyze the characteristics of the relationships of Indian Ocean Dipole (IOD), ENSO (El-Niño-Southern Oscillation) with East Asian summer monsoon. The results show: 1) Different East Asian summer monsoon index is different from different sea surface temperature index. For example, the Iljp index defined by the wind field reflects the ability of the Indian Ocean IOD to be stronger than Isn. 2) The same East Asian summer monsoon index and DMI, Nino3 index were associated with significant variation characteristics, IOD and ENSO have opposite effects on summer monsoon. The East Asian summer monsoon index had a good positive correlation with DMI before the 1990s, and since the late 1990s, the monsoon index was negatively correlated with the index of IOD, which was inversely related to the Nino3 index. The relationship between the East Asian summer monsoon with IOD, ENSO inter annual variation is characterized that one stronger and the other will become weaker. 3) From the view of spatial point, the different East Asian summer monsoon indexes are affected by the Indian Ocean and the Pacific Ocean temperature is different, and the sea surface temperature of the monsoon is not exactly the same. In the monsoon strong years, ENSO appears its positive phase over the Pacific Ocean, and the SST over the equatorial Indian Ocean is too cold. In the monsoon weak years, three East Asian summer monsoon indexes to the corresponding index of the sea temperature mode are different, Equatorial Indian Ocean as a whole warmer.