广东沿海降水长期变化特征与极值分析——以汕尾、广州、阳江3市为例

Analysis of the Characteristics and Extreme Value of Rainfall in Three Coastal Cities of Guangdong Province

利用汕尾站、广州站和阳江站1953-2008年56a的逐月降水量、逐月的日最大降水量作为基本资料,探讨广东省降水量的时空分布特征、长期变化趋势及突变分析。Morlet小波变换表明各城市降水量存在着7.8a和11a等周期变化,与厄尔尼诺和太阳黑子的运动周期相关。其次运用皮尔逊Ⅲ型分析3城市的最大日降雨量的极值分布情况,其中阳江站5年一遇的年最大日降水量300mm,达到特大暴雨的标准。M-K检验表明阳江站和广州站降水量分别于1971、1981年发生突变,年降水量由少雨期进入多雨期,且R/S分析表明其增长趋势持续至今,但不同站点有各自的变化特点。

By using the monthly rainfall data and the maximum daily precipitation data in each month of Shanwei Station, Guangzhou Station and Yangjiang Station during 1953-2008, the characteristics of spatial distribution, the long term trend and abruption are discussed. The result shows that： Morlet wavelet transform was applied to the analysis of the 56 years （1953-2008） monthly precipitation, changes in multi-time scale of monthly precipitation has probed. The periodic variances of precipitation of the three stations comprise long term variances such as 7.8a and 1 la, and 2a period is less significant. Based on the theory of distribution of extreme values we compute the maximum daily precipitation in the year in three stations and analyses the difference. With return periods of 2 years, the statistical curves of Pearson-Ⅲ distribution show that the maximum daily precipitation in the year of Shanwei Station, Guangzhou Station and Yangjiang Station are 170 mm, 110 mm and 190 mm. Yangjiang Station is up to 300mm with return periods of 5 years. The Mann-Kendall （M-K） test is used to examine the precipitation trend and detect the abruption of these datasets, there were breaking points appeared for the precipitation of Guangzhou Station and Yangiiang Station, Guangzhou Station was in 1981 and Yangjiang Station was in 1971, and both of them changed from the dry period to the dry period. The M-K test shows that the precipitation of the three stations appeared the fluctuating upwardly, and varied differently. Base on R/S analysis, the Hurst exponents of the stations were beyond 0.5, which indicated that all stations had evident Hurst phenomena, a durative on the whole. It means that the precipitation of the three stations had a trend componet, a persistent increasing trend. And there is some difference of the Hurst exponents among Shanwei Station, Goungzhou Station and Yangjiang Station.