东江流域汛期降水时空分布的非均一性特征

Characteristics of Inhomogeneity of Spatio-Temporal Distribution of Rainfall During the Flood Season of Dongjiang River Basin

利用东江流域13个气象观测站1967—2011年的逐月降水量资料,对流域内汛期降水量的时空分布非均一性进行了分析。结果表明:流域内汛期各时段降水量无明显增加趋势,年际、年代际变化明显;降水量的时空间分布与其均方差均呈显著的正相关关系;各时段降水量的站间偏度系数和各站偏度系数均以正偏为主,峰度系数多为负值,且站间偏度和峰度系数皆具有明显的年代际变化特征;汛期各时段降水量均有88.9%的年份在空间上服从正态分布;汛期有95.6%的气象站降水量服从正态分布、前汛期和后汛期有93.9%的气象站降水量服从正态分布。未能通过正态性检验的年份和站点,多是由于偏度系数不能满足条件。

Using monthly rainfall data in 1967 -2011 from 13 observation stations in the Dongjiang River basin, this work studies the inhomogeneity of the spatio-temporal distribution of rainfall during the flood season of the basin. The results are shown as follows. No significant trends of rainfall increase can be found in different sections of time during the season though interannual and interdeeadal variations are substantial. The spatio-temporal distribution of rainfall is much positively correlated with its mean square error. For the rainfall in individual sections of time, the skewness coefficients for individual stations and between the sta- tions are mainly positive while the peak coefficients are mostly negative. Besides, they vary greatly on the in- terdecadal scale. The rainfall in individual sections of time follows a normal spatial distribution in 88.9% of the years. During the annually first and second flood season, the rainfall follows a normal distribution at 93. 9% of the observation stations. Failure for some years and stations to pass the normal distribution test is mostly caused by a skewness coefficient that does not meet the conditions.