Influence of the convection over the South China Sea on the summer precipitation of Shandong Province

Abstract

The pentad average minimum outgoing longwave radiation (OLR) data over the northern South China Sea (SCS) are selected as indexes to analyze the intensity of the convection connected with the SCS monsoon onset. Statistic analysis demonstrates that the index can account for the intensity of the SCS monsoon about, at least, 75%. A significant negative correlation (confident level over 90%) between Shandong’s summer rainfall and the index is found only in the period of 24–26 pentads and limited to the area above the deeper water basin of the SCS (10°–20°N, 110°–117.5°E). Thus the minimum OLR over the deeper water basin during 24–26 pentads can be used as a valuable predictor for the long-lead forecast of the precipitation. The 500hPa geopotential height data in the Northern Hemisphere for the period from 1951 to 2000 are used in order to characterize the physical mechanisms involved. The composite anomalies of the 500hPa level allow for the identification and detection of the teleconnection of the East Asia-North America (EAP) pattern that is responsible to some extent for the interannual variability of the precipitation of Shandong Province. Besides, the interannual differences of the intraseasonal variations (ISV) of OLR and their northward transmission probably make a contribution to the position of the subtropical high which is vital for the summer rainfall in the province.