El Ni?o Occurrence and Sub-Struface Ocean Temperature Anomalies in the Pacific Warm Pool
厄尔尼诺的发生与赤道西太平洋暖池次表层海温异常

The close relationship of the El Nio occurrence with the positive anomalies of the sub-surface ocean temperature (SOT) in the Pacific warm pool region is studied through the data analyses. It is shown that there are continued positive anomalies of SOT in the warm pool region prior to the occurrence of El Nio event; The outbreak of El Nio event is directly associated to the eastward propagation of positive anomalies of SOT in the warm pool region and expanding to the sea surface in the equaorial eastern Pacific, so that the positive anomalies of SOT in the warm pool region and its eastward propagation are important factors to cause El Nio event. It is also clear that the reason to cause the eastward propagation of anomalous SOT in the warm pool region is the westerly wind anomalies over the equatorial western Pacific and their eastward expansion.