Heavy rainfalls over East Asia

Abstract

AbstractThe mean annual and monthly frequency distribution of heavy rainfalls for the period 1971–1980 are investigated over the whole of East Asia, including Japan, China, Korea, USSR, and Hong Kong. The highest frequency region (< 10 times per year) is shown to be located along the southern coast of Japan. The second highest region (< 8 times per year) is located along the southern coast of China. The high‐frequency area advances northward over China during the summer monsoon season, in accordance with the northward advance of the ‘Mei‐yü frontal zone’. Maps of the axes of high‐frequency heavy rainfall areas (frequency per 10‐day period) and of maximum‐frequency 10‐day periods at each station, clearly reveal the intra‐seasonal shift of the heavy rainfall area during the summer monsoon season.According to the dominant causes of heavy rainfalls, four regions are identified. The investigated area is also divided into three regions (I‐III) with respect to the annual frequency distribution of heavy rainfalls. Based on these regional divisions, the northern limit of the influence of the ‘Mei‐yü front’ is determined in terms of heavy rainfall occurrence.