Characteristics of intra-storm temporal pattern over China

To describe the characteristics of intra-storm temporal distributions of rainfall, minute resolution rainfall data were collected from 14 weather stations in China covering nearly 40 years. A total of 10 256 storms with precipitation amounts greater than 10 mm were analyzed. Based on a dynamic K-means cluster method and the time to peak index, the storms were divided into four hyetograph types: Rainfall concentrated early in the storm (Type I); rainfall concentrated in the middle of the storm (Type Ⅱ); rainfall concentrated at the end of the storm (Type Ⅲ); and rainfall distributed uniformly over time (Type IV). Type I storms occurred most frequently (47.1%), followed by Type Ⅱ (21.2%), Type Ⅲ (15.3%), and Type IV (16.4%). In summer, Type I storms had a normalized occurring frequency of 52.2%, suggesting that Type I storms were the most prevalent storm type during the summer. In winter, all four storm types occurred with similar frequencies. Type I storms were characterized by shorter durations and higher intensities, whereas Type IV storms had longer durations and lower intensities. The average duration, intensity, and the maximum 30 min intensity for Type I storms were 19.2 h, 2.8 mm/h, and 20.3 mm/h, respectively, whereas that for Type IV storms were 30.0 h, 1.4 mm/h, and 8.6 mm/h.