RELATIONSHIP BETWEEN TROPICAL SST CHANGE AND MONSOON DEVELOPMENT OVER PLATEAU

By using NOAA OLR data and NCEP/NCAR reanalysis grid data, the relationship of tropical Pacific and Indian Ocean SST background field changes and the development of monsoon over the Plateau are analyzed. Results show clearly that the SSTA increase on the Bengal gulf, South Sea and West Pacific warm pool in spring is favorable to the development of the summer Plateau monsoon, while the increase in the eastern equatorial Pacific SSTA has the opposite effect. The evolutionary characteristics of the prophase and synchronous SSTA fields, wind fields and OLR fields are also analyzed. Results show that there is great difference in the tropical background field between weak and strong monsoon years over the Plateau. During the development of Plateau monsoon from spring to summer, SSTAs over the Bengal gulf, South Sea and West Pacific are positive, but negative over the eastern equatorial Pacific at the same time, displayed the characteristics of La Nina; and vice versa, displayed the characteristics of El Nino.