Characteristics of Summer Precipitation in Beijing in the Context of Urbanization
The summer accumulated rainfall amount in urban areas concentrates in the evening to midnight (16-23pm LST), the greatest accumulated rainfall amount appears at 16-20pm, and the second at 21-22pm. The rainfall events appears the most frequent at 18-22pm, and the second in the morning about 4-6am. The rainfall events often appears from the evening till after midnight (17pm-02am), consisting of short duration rainfall events, i.e., less than 7 hours. During 16-18pm, it is primarily the rainfall events less than 3 hours, which is mainly convective weather with the greatest intensity, and having great contribution to accumulated rainfall amount. During 17-21pm, and after midnight(3-4 am)there is high value of accumulated rainfall, and intensity less than at 16-18pm. The accumulated rainfall of short duration is obviously greater than long duration, where rainfall events lasting less than 7 hours have the major contribution to accumulated rainfall amount.
In the urban areas, the precipitation shows a tendency of short duration time and high intensity. Accumulated rainfall amount of short duration events increases gradually, while that of long duration events decreases significantly.