摘要
利用历史观测数据，研究了印度洋海表温度（ＳＳＴ）的季节变化特征，证实赤道印度洋和东太平洋ＳＳＴ年际变化有显著的正相关，指出这种正相关是由于沿赤道印度洋上空纬向季风环流和太平洋上空Ｗａｌｋｅｒ环流之间显著的耦合造成的。这两个异常的纬向环流圈之间的耦合形式看起来很象是存在于赤道印度洋和太平洋上空的一对齿轮（简写为ＧＩＰ），当一个作顺时向变化时，另一个则作反时向变化。文中还证明ＥＮＳＯ事件与ＧＩＰ的年际异常存在很好的对应关系，暖事件时ＧＩＰ为反向运转；冷事件时ＧＩＰ为正向运转；异常的ＧＩＰ的啮合点位于印尼群岛附近。对８０年代以来的ＥＮＳＯ事件的分析表明，每次事件前期异常的ＧＩＰ的啮合点首先出现在印度洋上空，然后逐渐传入太平洋，引起ＧＩＰ东侧的大气纬向风ｕ和ＳＳＴ同时发生异常变化。当这种风场和ＳＳＴ的异常变化发展东传到达赤道中东太平洋时，导致ＥＮＳＯ事件最终出现。本文由此指出印度洋上空纬向环流的异常可以通过印度洋和太平洋上空大气系统的齿轮式耦合去影响赤道中东太平洋的海－气相互作用并触发ＥＮＳＯ事件发生。
Observation data were employed to study the seasonal variation of the sea surface temperature (SST) of the Indian Ocean It is shown that there exists significant positive correlation in SST anomalies between the equatorial Indian Ocean and the eastern equatorial Pacific Ocean; and such significant correlation is associated with the strong coupling between the monsoonal zonal circulation over the equatorial Indian Ocean and the Walker circulation over the Pacific Ocean The coupling of these two circulation cells works in a way much like a pair of gear operating over the equatorial Indian and Pacific, which is denoted as “GIP” ENSO events are shown to be closely linked to this GIP: a “positive” rotating of the GIP corresponds to a cold ENSO event; whereas its reversed rotating corresponds to warm ENSO events; and the “gearing point” of the two cells is located by the Indonesia archipelagoes The evolutions of the ENSO events after 1980 are analyzed It is shown that for each of these events the “gearing point” of the GIP appears firstly over the equatorial Indian Ocean It then propagats eastward into the western Pacific, resulting in the appearance of the anomalies in the equatorial zonal wind and SST to the east of the gearing point When the gearing point propagates further eastward, and the associated anomalous SST and u at 850 hPa approachs the dateline, ENSO event over the equatorial eastern Pacific occurs It is therefore concluded that the anomalies in the monsoonal zonal flow over the Indian Ocean can affect the air-sea interaction over the central and eastern equatorial Pacific by the virtue of the GIP and may trigger off the occurrence of ENSO events
出处
《大气科学》
CSCD
北大核心
1998年第4期470-480,共11页
Chinese Journal of Atmospheric Sciences
基金
国家自然科学基金
关键词
赤道
印度洋
太平洋
海气耦合
齿轮式
厄尔尼诺
anomalous Walker circulation anomalous zonal monsoon circulation gearing of circulation
