固原市日降水量极大值的概率分布特征

The Probability Distribution Characteristics of Maximum Daily Precipitation in Guyuan

选用Gumbel(耿布尔)分布作为已知分布函数,利用固原市4站1957～2010年的日降水量年极大值资料,对拟合参数进行了估计,并通过皮尔逊检验法作拟合程度检验,得到固原各站日降水量年极大值的分布函数,最后以这一分布作为它的理论分布推断多年一遇的最大日降水量。结果表明,固原市3站(固原基准站、西吉、泾源)日降水量年极大值遵循Gumbel分布,并推断出它们50～200年一遇的可能最大日降水量,其50年一遇的最大日降水量与多年观测的最大日降水量相比,固原偏少2.4 mm,西吉、泾源分别偏多7.7、1.3mm,相对误差在1%～11%;而隆德站日降水量极大值分布不符合Gumbel分布。

Gumbel-distribution was chosen as known distribution function,data of maximum daily precipitation during 1957-2010 in four stations of Guyuan were used to estimate fitting parameters,and Pearson test was used to test fitting degree,the distribution function of maximum daily precipitation in each station of Guyuan was got,finally,the distribution was viewed as theory distribution to deduce maximum daily precipitation in many years.The results showed that maximum daily precipitation of three stations of Guyuan（Guyuan base station,Xiji,Jingyuan） followed the distribution of Gumbel,and deduced the maximum daily precipitation in 50-200 years,among which 50 years of maximum daily precipitation was compared with observed maximum daily precipitation for many years,Guyuan was less,2.4 mm,Xiji and Jingyuan were more,7.7 and 1.3 mm,relative error was 1%-11%;however,the distribution of maximum daily precipitation in Longde Station was not in accordance with Gumbel-distribution.