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, spatialdistributions of frequency for 20 mm h^-1 and 50 mm h^-1 precipitation were analyzed, and the criteriaof short-duration rainfall events and severe rainfall events are discussed. Furthermore, the percentile methodwas used to define local hourly extreme precipitation; based on this, diurnal variations and trends in extremeprecipitation 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 occurmost frequently in late afternoon and/or early evening. In the GuizhouPlateau and the Sichuan Basin, the maximum frequency of extremeprecipitation events occurs in the late night and/or early morning. And inthe western Sichuan Plateau, the maximum frequency occurs in the middle ofthe night.The frequency of extreme precipitation (based on hourly rainfallmeasurements) has increased in most parts of eastern China, especially inNortheast China and the middle and lower reaches of the Yangtze River, butprecipitation has decreased significantly in North China in the past 50years. In addition, stations in the Guizhou Plateau and the middle and lowerreaches of the Yangtze River exhibit significant increasing trends in hourlyprecipitation extremes during the nighttime more than during the daytime.