A STUDY ON VARIABILITY OF SEA SURFACE TEMPERATURE IN TROPICAL PACIFIC, INDIAN OCEAN AND RELATED AIR CIRCULATION

摘要

Canonical Correlation Analysis (CCA) was a-dopted in the present paper to study the of Sea Surface Temperature (SST) in the tropical Pacific, Indian Ocean and related air circulation. The results show that on the seasonal time scale, El Nino events can be divided into two types: the east one and the middle one. For the middle type the SST variations appear contrarily in the tropical Pacific and Indian O-cean, and the anomalous SST decreases in the east but increases in the northwest and south-middle of the tropical Indian O-cean, specially in the east of Madagascar Island. And vice versa. On annual time scale, when the Asian continent high gets stronger and the deepened Aleutian low shifts southeastward, both of them trigger an onset of the El Nino events. Contrarily, the La Nina events take place. On decadal time scale, there are two basic modes of air-sea system over the tropical Pacific and Indian Ocean. Firstly, when the Asian continent high gets stronger and deepened Aleutian low shifts southeastward, the anomalous SST increases in the middle and east of the proical Pacific, extending to the subtropical regions, and so in most of the tropical Indian Ocean, specially in the northeast of Madagascar Island and nearby. And vice versa. Secondly, when the Asian continent high gets stronger in the north and the Aleutian low decreases fixedly or even disappears, the anomalous SST decreases slightly in middle of the tropical Pacific and the temperate northern Pacific but increases weakly in other regions, the anomalous SST increases in the south but decreases in the north of the tropical Indian O-cean, and the SST increases more obviously in southeast of Madagascar Island. And vice versa. The linear trends of glob- al warming seems to play a certain role for the El Nino onsets.