中国南方夏半年湿期概率特征及其极值风险分析

The probability analysis for wet spell and its extreme risk during summer over southern part of China

以中国南方诸代表站近40 a(1965—2004年)夏季(5—9月)逐日降水资料为研究对象,探讨了夏半年各站湿期游程及其极端值的概率分布最佳模式。在对各站湿期游程分别验证指数分布的基础上,作耿贝尔(Gumbel)极值分布和广义帕雷托分布(GPD)拟合,进而对两者的拟合效果进行比较。并由此对湿期长度估计其不同重现期(如20 a一遇、50 a一遇和100 a一遇)的极端湿期长度的分位数概率。经K-S方法的统计检验,证明GPD分布拟合效果较好,能更加精确的模拟出中国南方夏季的极端连雨日数及其概率。

The optimal models of probability distribution for durations of continuous rainfall days and its extreme value are investigated during semiannual summer at several representative stations,which have the data for summer（May to Sept.） during 1965—2004,over southern China in this paper.According to optimal estimation for statistical parameters,the extreme value distributions for durations of continuous rainfall days at each station are finely fitted by using Gumbel distribution and generalized Pareto distribution because each station is almost consistent with the exponential distribution,and the quartiles and their probabilities of extreme values（e.g.probabilities as 0.05,0.02 and 0.01） of the extreme durations of continuous rainfall days at each station are estimated.It has been proved by using K-S statistical test that the GPD distribution results are more suitabe to simulate the probability features for extreme durations of continuous rainfall days during summer over southern China.