Characteristics Of Tropical Cyclone Extreme Precipitation And Its Preliminary Causes In China’s Southeast Coast

In this paper, a mature tropical cyclone precipitation objective identification method (OSAT) is used to identify the tropical cyclone (TC) precipitation from the daily station precipitation in the southeast coast of mainland China (Zhejiang, Fujian and Shanghai) between1958and2012. TC extreme precipitation is defined as a statistically extreme precipitation reaching a certain level. It is to summarize the characteristics of TC extreme precipitation and conclude the initial causes that could promote TC extreme precipitation. The main conclusions are as follows:1、The TC extreme precipitations in China’s southeast coast between1958-2012exhibits uneven spatial and temporal distribution:As for the spatial distribution, there is a decreasing trend from the coast to the inland. And the TC extreme precipitation zones can be divided into three major parts, namely the northern, central and southern part separately, whose region segmentation points are Wenzhou and Fuzhou respectively, while the strongest intensity of extreme precipitation is in the central and the weakest in the northern part; In temporal distribution, both intensity and frequency of TC extreme precipitation have increased significantly in recent years.2、The characteristics of TC that affecting three main TC extreme precipitation zones respectively show that:The central type TC displays the strongest intensity among the three types, producing extreme precipitation in the landing day while the path is West-Northwest. Most of the south type TCs present the Northwest way to landing the southeast coast, while the route of the north type TC is more irregular. The moving speeds of three TCs have no significant difference.3、The terrain role is a key factor in strengthening TC extreme precipitation:the three key areas which are bounded with Fuzhou and Wenzhou correspond with North Hill, South Hill to the northeast of Mountain JiuFeng, Mountain DaiYun in the south of Fujian province respectively, when the windward slope contributes to the formation of precipitation extreme centers.4、All of the intensity, speed, warm core structure and the path of tropical cyclones are important factors that affecting the TC extreme precipitations. Overall, the tropical cyclones with stronger strength, slower moving speed and more northerly path tend to generate larger tropical cyclone extreme precipitation.5、As for the environmental factors, the interaction between TC and westerly trough, southwest monsoon systems is an important factor that contributing to TC extreme precipitation. The configuration that combining low-level moisture convergence with high-level divergence promotes convective activity, producing more precipitation.