中国大陆台风远距离极端降水的基本特征

台风远距离极端降水可以分为极端小时降水(Extreme Hourly Precipitation,EXHP)和极端持续性强降水(Extremely Persistent Heavy Rainfall,EPHR)两类,因其作用距离远、机理复杂,是强降水业务预报中的重大挑战。为了加深对台风远距离极端降水特征的认识,本文利用2009—2019年中国自动站融合CMORPH卫星降水数据、热带气旋的最佳路径数据集,揭示了中国大陆EXHP和EPHR事件的基本特征。结果表明:环渤海、长江中下游、四川盆地是由台风远距离降水引发的EPHR和EXHP事件的3个高发区,强降水持续时间≥5 h为台风远距离EPHR的判别标准,在3个不同的区域内,EXHP的阈值分别为34.05、30.52及27.19 mm·h^-1。EPHR的发生时次与EXHP重合率高。EPHR事件的持续时间最长可达44 h,最大累积降水量可达542.03 mm,而EXHP的小时降水量更强。环渤海地区极端降水多发于夜间到清晨,长江中下游地区多集中在上午,四川盆地则集中在凌晨。造成长江中下游远距离极端降水的最大台风强度在3个地区中最强。极端降水落区与台风的最远距离发生在环渤海地区,可达4 333.1 km。

Characteristics of typhoon remote extreme precipitation in Chinese Mainland

Typhoon remote precipitation can be divided into Extreme Hourly Precipitation (EXHP) and Extremely Persistent Heavy Rainfall (EPHR). Because of its long distance and complex mechanism, it is a major challenge in the operational forecast of heavy precipitation. In order to deepen the understanding of the characteristics of typhoon remote extreme precipitation, this paper reveal the basic characteristics of the EXHP and EPHR events in Chinese Mainland by using the CMORPH satellite precipitation data from 2009 to 2019 and the best path data set of tropical cyclones. Results show that the Bohai Rim, the middle and lower reaches of the Yangtze River, and the Sichuan Basin are three high incidence areas of EPHR and EXHP events caused by typhoon remote precipitation. The criterion for typhoon remote precipitation EPHR is that the duration of heavy precipitation more than 5 hours. In three different areas, the threshold values of EXHP are 34.05, 30.52, 27.19 mm·h^-1, respectively. The coincidence rate between the occurrence time of EPHR and EXHP is high. The duration of EPHR event can reach 44 h at most, and the maximum accumulated precipitation can reach 542.03 mm, while the hourly precipitation of EXHP is stronger. Extreme precipitation occurs frequently from night to morning around the Bohai Sea, mainly in the morning in the middle and lower reaches of the Yangtze River, and in the early morning in Sichuan Basin.The maximum typhoon intensity causing extreme precipitation in the middle and lower reaches of the Yangtze River is the strongest in the three places. The average typhoon moving speed of EXHP in the middle and lower reaches of the Yangtze River and Sichuan Basin is less than EPHR. The typhoon causing extreme precipitation can occur in the Bohai Rim at the longest distance, up to 4 333.1 km.