Regional differences of daily rainfall characteristics in East Asian summer monsoon season

Abstract

Regional differences of daily rainfall characteristics are examined during the East Asian summer monsoon season (May to August) over a 30-year (1961-90) period. It is found that the contribution of heavy rainfall with a daily total >50 mm to total seasonal precipitation exceeds 50% around Taiwan, in the northwestern part of Kyushu Island, coastal Southwest Japan, and the southern coast of China. It exceeds 40% in northern Korea, the middle of the Yangtze and lower Huai-he River Basins. On the other hand, daily rainfall characteristics in Southwest, Northwest and North China are quite different from these regions. In Southwest China, although seasonal total precipitation is considerably large (> 1000 mm), the contribution of daily heavy rainfall to total precipitation is only less than 20% to the west of 105°E. In Northwest China, both total precipitation and contribution of daily heavy rainfall to total precipitation are small. In North China, precipitation by weak daily rainfall with a daily total < 20 mm is relatively high. The seasonal changes of heavy rainfall events are also examined. In general, the area of both maximum precipitation and heavy rainfall occurrence progresses northward from early June to late July in the major part of both East China and Japan in accordance with northward displacement of Baiu/Meiyu season. But some different features are found to the west of ~110°E in China.