The Effect of the Westerly Anomalies over the Tropica Pacific on the Occurrence of ENSO Events
热带太平洋西风异常对ENSO事件发生的作用

This paper analyzes the westerly anomalies over the tropical Pacific and their effect on the warming of the sea surface temperature (SST) in the equatorial central and eastern Pacific in the processes of two ENSO events, occurred in the 1980's and compares them using the observed data. The analyzed results show that in the occurring processes of these two ENSO events, there were the larger westerly anomalies over the equatorial western Pacific and they propagated from the equatorial western Pacific toward the equatorial central and eastern Pacific. With the propagation of the westerly anomalies from the east to the west, the sea surface of the equatorial central and eastern Pacific was successively warming. The analyzed results also show that the strength of the westerly anomalies in the occurring process of the 1982/1983 ENSO event was stronger than that in the occurring process of the 1986/1987 ENSO event resulting in a much stronger ENSO event during 1987/1983 than the 1986/1987 ENSO event. In order to explain the effect of the westerly anomalies over the tropical western Pacific on the occurrence of ENSO events in the equatorial central and eastern Pacific, the IAP Pacific General Oceanic Circulation Model (IAP-POGCM) is used to simulate numerically the effect of the westerly anomalies on the occurrence of ENSO event. The simulated result shows that the westerly anomalies over the tropical Pacific play an important role in the eastward propagation of the warm sea water in the equatorial Pacific and the warming in the equatorial central and eastern Pacific.