Temporal and Spatial Characteristics of Extreme Hourly Precipitation over Eastern China in the Warm Season

Based on hourly precipitation data in eastern China in the warm season during 1961--2000, spatial distributions of frequency for 20 mm h-1 and 50 mm h-1 precipitation were analyzed, and the criteria of short-duration rainfall events and severe rainfall events are discussed. Furthermore, the percentile method was used to define local hourly extreme precipitation; based on this, diurnal variations and trends in extreme precipitation were further studied. The results of this study show that, over Yunnan, South China, North China, and Northeast China, the most frequent extreme precipitation events occur most frequently in late afternoon and/or early evening. In the Guizhou Plateau and the Sichuan Basin, the maximum frequency of extreme precipitation events occurs in the late night and/or early morning. And in the western Sichuan Plateau, the maximum frequency occurs in the middle of the night. The frequency of extreme precipitation (based on hourly rainfall measurements) has increased in most parts of eastern China, especially in Northeast China and the middle and lower reaches of the Yangtze River, but precipitation has decreased significantly in North China in the past 50 years. In addition, stations in the Guizhou Plateau and the middle and lower reaches of the Yangtze River exhibit significant increasing trends in hourly precipitation extremes during the nighttime more than during the daytime.