STUDY ON THE RELATIONSHIP BETWEEN THE DECADAL VARIATIONS OF ANNUALLY FIRST RAINY SEASON PRECIPITATION OF GUANGXIAND SEA SURFACE TEMPERATURE OF INDIAN OCEAN IN SOUTHERN HEMISPHERE

Decadal circulation differences between more and less rainfall periods in the annually first rainyseason of Guangxi and their association with sea surface temperature (SST) of the austral Indian Ocean areinvestigated by using the NCEP/NCAR reanalysis data. The results are shown as follows. A pattern inwhich there is uniform change of the Guangxi precipitation shows a 20-year decadal oscillation and a3-year interannual change. In contrast, a pattern of reversed-phase change between the north and the southof Guangxi has a 6-year interannual periodicity and quasi-biennial oscillation. In the period of moreprecipitation, the surface temperature in Eurasia is positively anomalous so as to lead to stronger lowpressure systems on land and larger thermal contrast between land and ocean. Therefore, the air column ismore unstable and ascending flows over Guangxi are intensified while the Hadley cell is weakened.Furthermore, the weaker western Pacific subtropical high and South Asia High, together with a strongercross-equatorial flow, result in the transportation of more humidity and the appearance of moreprecipitation. The correlation analysis indicates that the Indian Ocean SST in Southern Hemisphere isclosely associated with the variation of the seasonal precipitation of Guangxi on the decadal scale byinfluencing the Asian monsoon through the cross-equatorial flow.