1998 Volume 71 Issue 1 Pages 59-71
High negative correlation between summer rainfall anomaly in the Yangtze Valley and the middle reaches of the Yellow River in China is shown. Rainfall Anomaly Index (RAI) and the Student's t-test revealed a decadal fluctuation of RAI in the Yangtze Valley at the end of the 1970s. The results concerning correlation between RAI and atmospheric circulation indices show that the variation of summer RAI in the Yangtze Valley is closely related to western Pacific subtropical high index (20-30°N, 130-170°E) at 500 hPa-level in May and westerly zonal index (40-60°N, 90-170°E) at 500 hPa-level in July. The decadal fluctuation of RAI at the end of the 1970s in the Yangtze Valley corresponds to the fluctuation of westerly zonal index in July and western Pacific subtropical high index in May. The impact of sea surface temperature (SST) (EQ-14°N, 130-150°E) in the western Pacific Ocean on RAI in the Yangtze Valley is also discussed. The negative correlation between the SST in June and summer RAI in the Yangtze River at the end of 1970s exhibits a clear atmospheric-oceanic teleconnection. It is closely associated with rainy conditions in the Yangtze Valley during El Niño in the period 1978-1991.
