Analysis of Causes and Seasonal Prediction of the Severe Floods in Yangtze / Huaihe Basins during Summer 1991

The present paper shows that a seasonal prediction for the large scale flooding and waterlogging of the mid-lower Yangtze/ Huaihe River basins in the summer of 1991 made successfully in early April 1991. The seasonal fore-casting method and some predictors are also introduced and analyzed herein. Because the extra extent of the abnormally early onset of the plum rain period in 1991 was unexpected, great efforts have been made to find out the causes of this abnormality. These causes are mainly associated with the large scale warming of SST surrounding the south and east part of Asia during the preceding winter, while the ENSO-like pattern of SSTA occurred in the North Pacific. In addition, the possible influence of strong solar proton events is analyzed. In order to improve the seasonal prediction the usage of the predicted SOI in following spring / summer is also introduced. The author believes that the regional climate anomaly can be correctly predicted for one season ahead only on the basis of physical under-standing of the interactions of many preceding factors.