福建省台风灾害风险评估与区划

利用1980—2013年7月1日—9月30日中国东南地区818个国家地面气象站小时降水资料以及台风6 h路径观测数据分离出台风降水后，采用最大似然估计法得到台风小时降水Gamma概率密度函数分布的形状参数α和尺度参数β，并对代表站点上Gamma分布模拟的小时降水概率分布与观测的小时降水频率分布进行对比分析；最后，基于Gamma分布模拟，得到台风小时降水总的降水概率分布特征以及不同台风影响距离和台风强度影响下超过给定阈值的降水累积概率分布与极端降水阈值。结果表明:我国东南地区台风降水总的特征是小时降水超过5 mm多发地区位于华南、华东沿海地区；其余大部分地区不易发生超过5 mm的小时降水量；广东沿海、广西南部、海南西北部，小时降水超过10 mm的累积概率为10%~15%；小时雨量超过20 mm阈值的概率极低；在近距离台风影响下，随着台风强度增大，95%累积概率小时降水阈值为15~20 mm的区域由福建和广东沿海以及海南变为湛江和海南，而阈值为10~15 mm的地区由两广浙闽地区变为广东、福建和江苏沿海以及浙江；就远距离台风而言，随着台风强度增大，东南地区出现台风降水的区域逐渐由东南沿海向内陆延伸；海南、广东、福建和江西为远距离强台风影响下95%累积概率对应的小时降水阈值较高地区。

Changes in tropical cyclone precipitation over China

First, we separated the typhoon precipitation from hourly precipitation data at 818 national meteorological stations by referring the 6-hour CMA-STI tropical cyclone best-track data between 1 July and 30 September from 1980 to 2013. Secondly, we employed the maximum likelihood estimation method to obtain the shape parameter α and scale parameter β of typhoon precipitation probability density in a Gamma distribution, then performed a comparative analysis of hourly precipitation probability distribution observed and simulated by the Gamma distribution at representative stations. Lastly, based on the simulation of the Gamma distribution, we obtained the probability distribution of typhoon precipitation, and the cumulative probability distribution of precipitation exceeding given thresholds and the series thresholds of extreme typhoon precipitation under different influence distance and different intensity of typhoon. The results show that, generally, the areas of the coastal regions of south and east China have the largest probability of 5 mm threshold precipitation. The rest of the regions have a low probability of 5 mm threshold precipitation. The cumulative probability with hourly rainfall over 10 mm threshold is between 10% and 15% in the coastal region of Guangdong, south part of Guangxi and northwest part of Hainan province. The probability with hourly rainfall more than 20 mm threshold is very low in southeast China. With the increase of the intensity of the short distance typhoons, the regions where the hourly rainfall of 15 to 20 mm threshold with 95% cumulative distribution function (CDF) change from Hainan and the coastal region of Fujian and Guangdong to Zhanjiang and Hainan. The regions of hourly precipitation 10 to15 mm threshold with 95% CDF change from Guangdong, Guangxi, Fujian and Zhejiang to Zhejiang and the coastal area of Jiangsu, Guangdong and Fujian provinces. With the increase of the intensity of the long distance typhoons, the areas affected by typhoon precipitation gradually extend from the southeast coast of China to inland, whereas the regions with higher hourly precipitation threshold with 95% CDF are Hainan, Guangdong, Fujian and Jiangxi provinces.