热带气旋降水重现期估算研究

Estimation on return period of tropical cyclone precipitation

强降水是热带气旋灾害的重要致灾因子,热带气旋的降水重现期估算对灾害管理具有重要的意义。首先,基于《热带气旋年鉴》(1951-2009年)中存档的纸质总降水等值线图,在GIS系统中进行了数字化,并利用距离平方反比法插值得到了784场1 km×1 km网格的热带气旋的降水栅格分布图。其次,基于极值理论,估算了全中国和各1 km×1 km网格热带气旋各重现期下的年总降水量(ATP)和年最大降水量(AMP)。结果表明,ATP和AMP呈自东南沿海向西北内陆递减。然后,定量探讨了可能影响重现期估算结果的因素。结果表明,Gumbel分布函数能较好地估算重现期;样本量越大,重现期估计可靠性越高;相同重现期样本下,样本的采样时段差异会引起结果估计的差异;1km-ATP重现期估计值在沿海地区及晋-冀-辽-蒙地区对样本选取较为敏感,而1 km-AMP在晋-冀-辽-蒙一带、浙北-苏南、辽东以及长江以南等斑块区域对样本较为敏感。

Strong precipitation is one of the major hazards caused by tropical cyclone,and the estimation of its return period( RP) is of great significance to disaster risk assessment. In this paper,the total rainfall contours of each TC were digitized in GIS from TC Yearbooks( 1951- 2009) archived by Shanghai Typhoon Institute.Following that,the precipitation grids with 1 km × 1km resolution of 784 TCs were interpolated from the digitized contours with inverse distance squared method. Then the RPs of annual total precipitation( ATP) and annual maximum precipitation( AMP) of each 1 km × 1 km grid,and their totals over land of China,were estimated according to the extreme value theory. RP estimation results show that,both ATP and AMP decreases from coastal areas to inland area. The factors that may influence the reliability of RP estimation were also analyzed,and it is found that,( 1) Gumbel distribution can estimate the return period with satisfactory significance statistically,( 2)larger sample size will result in more reliable estimation of RPs,and for same RP sample,the variance of sampling time interval may lead to different estimation results( 3) RP estimation for 1 km-ATP is more sensitive to sampling size or time interval in most coastal areas,and some inland areas such as Shanxi,Hebei,Liaoning and InnerMongolia. Regarding 1 km-AMP,sensitive areas are widely distributed in Shanxi,Hebei,Liaoning and Inner Mongolia,and also a belt stretching from north of Zhejiang to the south of Jiangsu,east of Liaoning,together with some scattered patches across south of the Yangtze river.