Astronomical Factor for the Occurrence of the Extraorchary Flood along the Yaugtze Huaihe Rivers During Early Summer,1991─The Bursts of Solar Proton Flares

The relationship between anomalous circulation in the Northern hemisphere and a series of solar proton flares occurred before the severe floods along the Yangtze-Huaihe Rivers during early summer, 1991 is researched. The results indicate that the continuous bursts of the large proton flares on solar disk is believed to be an important astronomical factor for the occurrence of the floods. The solar proton flares may trigger or intensify the process of the southward shift of cold air from polar vortex, the eastward shift of the low southwest jet flows and the west-hor-thward shift of the subtropical high in the west Pacific. Due to the frequent meeting of the cold and hot airflow along the middle-lower reaches of Yangtze River and Huaihe Rivers, it formed frequent processes of the heavy and heaviest rainfalls and then lead to the extraordinary flood along the Yangtze-Huaihe Rivers during early summer, 1991.