Spatial and Temporal Variation in Minimum Inter-event Time over Mainland China

Pluviograph precipitation records include wet periods and dry periods. Minimum inter-event time (MIT) is an index identifying individual rain event from pluviograph records. An event was defined as a duration of rainfall with the dry periods less than MIT. If the dry period in a duration equals or is greater than MIT, the duration was separated into two events. Event characteristics such as amount, duration, mean intensity and peak intensity are closely related to the MIT. At the same time, MIT is a critical parameter in the event-based stochastic precipitation simulation. Arbitrary separation, autocorrelation method, rank correlation method and exponential distribution method were mainly used in the previous research. Exponential distribution method generated reliable but highly variable MIT values across different regions in the world in previous research. Exponential distribution method was used for more than 2000 stations with hourly precipitation data to obtain MIT for the rainy season (May to Sep.) over mainland China. The seasonal variations of MIT for five regions in the southern part of China were also presented because stations in the northern part stopped the siphon type observation due to the snow in the cold season, resulting serious data loss for these stations in the cold season. Eleven climatology regions were divided. Results showed that for the rainy season, MIT varied from 8 hr to 15 hr with regions in the southern China larger than those in the northern China. Averaged MIT values over five southern regions are 10 hr for the spring (Mar. to May), 12 hr for the summer (Jun. to Aug.) and 20 hr for the autumn (Sep. to Nov.). MIT values for the autumn were the largest for all five southern regions ranging from 14 hr to 31 hr, with an average of 20 hr. Two regions including South China and Southwest China were with larger MIT for the spring than for the summer, whereas for the other three regions including Yangtze-Huai River Region, Yangtze-Han River region and South of Yangtze River region, MIT for the summer is larger than those for the spring, which may relate to the rain belt shift in the East Asia monsoon controlled area.