Changes in Duration-Related Characteristics of Late-Summer Precipitation over Eastern China in the Past 40 Years

Duration is a key feature of rainfall events that is closely related to rainfall mechanisms and influences. This study analyzes the decadal change in the duration-related characteristics of late-summer (July August) precipitation over eastern China during 1966-2005. Accompanying the southern-flooding and northern-drought (SFND) pattern of rainfall amount over the eastern China in recent decades, the duration-related rainfall structure also experienced significant changes. In North China, the frequency of short duration rainfall events decreased and their intensity increased. The decadal decreases of rainfall amount over North China are largely contributed by long duration rainfall events, especially those occurring between midnight and morning. In the mid-to-lower reaches of the Yangtze River valley, both the frequency and amount of long duration precipitation have significantly increased. The mean and maximum duration time of late-summer precipitation has increased 0.85 and 7.61 h, respectively. Considerable increases of rainfall amount of two kinds of precipitation, the short and medium duration rainfall events in the late afternoon and the long duration rainfall events in the early morning, contribute to the "southern-flooding." Despite the differences between the northern and southern region, there is a common feature of their decadal precipitation changes that the intensity of short duration rainfall in the late afternoon has shown an increasing trend.