The Relationship between the Summer Monsoon Circulation in East Asia and ENSO Cycle

The variation of East Asia summer monsoon circulation in different periods of ENSO cycle has been analyzed by using meteorological data from NCEP/NCAR and sea surface temperature data from NCAR. The normalized relative intensity, correlation and difference between the circulation of each year and the mean circulation are calculated and their relation with SST anomalies are discussed. The results show that there are obvious annual and decadal changes in East Asia summer monsoon circulation, and there are quiet good negative correlation between the normalized relative intensity of the summer monsoon circulation and SST in East Equatorial Pacific. Especially, the negative correlation between the summer monsoon circulation and SST in March and April is best. The northward extended latitudes of the south wind component at 850 hPa and the meridional circulation in East Asia summer monsoon region in June and July in the cool period of Nino1+2 SST is much different from those in the warm period of Nino1+2 SST. The meridional wind bigger than 2 m·s\+\{-1\} extends more northward and the upward flow of monsoon circulation in the cool SST period and East Asia summer monsoon is stronger in cool SST period then that in warm SST period.