Shift in the summer rainfall over the Yangtze River valley in the late 1970s

[1] The summer rainfall over the middle- lower valley of the Yangtze River and over the whole eastern China experienced a notable regime shift in about 1979. This change is consistent with a simultaneous jump- like change in the 500 hPa geopotential height (Phi500) over the northern Pacific. The rainfall over the Yangtze River valley is closely related to the Phi500 averaged over the area 20degrees -25degreesN, 125degrees -140degreesE, with a correlation coefficient of 0.66 for the period 1958- 1999. Since 1980, the subtropical northwestern Pacific high (SNPH) has enlarged, intensified, and extended southwestward. The changes in the SNPH are strongly associated with the variations of the sea surface temperatures (SSTs) of the eastern tropical Pacific and tropical Indian Ocean. The anomalies of these SSTs, responsible primarily for the shift of the summer rainfall over the Yangtze River through the changes in SNPH, precede the Phi500 signals with different leading times.