Diagnostic analysis of interdecadal changes of the summer monsoon in the south china sea

The onset dates and intensities for the South China Sea (SCS) summer monsoon over the past 51 years are established using the reanalyzed gridpoint data of NCEP and SST data from 1950 to 2000.As is shown in the t-test, the activities of the SCS monsoon (including the dates of onset and intensities) experienced a significant interdecadal change in the mid-1970s.The monsoon activity is closely related with the anomalies of the general circulation in the mid- and higher-latitudes but it is not related with those of the SST in tropical oceans before 1975.After 1975, the onset is earlier and the intensity is weaker and the SST anomalies in the tropical Indian Ocean and the Pacific Ocean have significant impacts on the activity of the SCS summer monsoon.These significant changes are thought to be associated with the interdecadal variation of SST over the oceans.