南印度洋副热带偶极模在ENSO事件中的作用

Influence of subtropical dipole pattern in southern Indian Ocean on ENSO event

南印度洋副热带偶极模(Subtropical Dipole Pattern,SDP)是印度洋存在的另一种很明显的偶极型海温差异现象,在年际和年代际尺度上均有十分明显的表现.而目前有关印度洋海气相互作用的研究主要集中在赤道印度洋地区,针对南印度洋地区的工作还比较少,特别是有关南印度洋海温与ENSO(EI Nino-Southern Oscillation)事件关系的研究.本文初步探讨了年际尺度上南印度洋副热带偶极型海温变化差异与ENSO事件的关系,发现SDP与ENSO事件有密切的联系,SDP事件就像连接正负ENSO位相转换的一个中间环节,SDP事件前后期ENSO的位相刚好完全相反.进一步,本文通过分析SDP事件前后期海温、高低层风、低层辐合辐散、高空云量和辐射等的变化特征研究了南印度洋偶极型海温异常在ENSO事件中的作用,结果表明:SDP在ENSO事件中的作用不仅涉及海气相互作用的正负反馈过程,还与热带和副热带大气环流之间的相互作用有关,特别是与东南印度洋海温变化所引起的异常纬向风由赤道印度洋向赤道太平洋传播的过程等有十分直接的关系;同时,SDP对ENSO事件的影响在很大程度上还依赖于大尺度平均气流随季节的变换.

Subtropical Dipole Pattern （SDP） in southern Indian Ocean is another significant dipolelike sea surface temperature anomalies（SSTA） phenomena besides tropical Indian Ocean dipole （TIOD）. It is very clear in interannual and interdecadal variations. But many recent studies have mainly aimed at the SST of equatorial Indian Ocean and less at southern Indian Ocean, especially less at the relationship between SSTA in southern Indian Ocean and El Nino-Southern Oscillation （ENSO）. Present works investigated primarily the correlation between the SDP and ENSO. It is found that SDP event act as a crucial linkage between positive and negative ENSO phases. The SSTAs in equatorial eastern Pacific Ocean are completely reversed before andafter SDP event. Further, we investigated the possible impact interannual scale by researching the anomalous characteristics convergence and divergence, total cloud amount, radiation and so the influence of SDP on ENSO involve feedback, but also the interaction betwee specially the eastward propagation of ano the Pacific Ocean. Otherwise, it also re climatic mean flow over the Indian Ocean SDP on ENSO event in sea temperature, wind, The results showed that not only the process of positive and negative air-sea n atmospheric circulation over tropical and subtropical, malous zonal wind from the equatorial Indian Ocean to lates, to some extent, to the transition of large-scale and Pacific Ocean.