北京地区暴雨气候特征及其变化分析

利用1961～2007年北京地区降水资料，采用气候倾向率、多项式曲线拟合和Morlet小波分析方法，对北京地区暴雨的气候特征及变化趋势进行了分析，结果表明:1）北京地区暴雨有明显的月变化特征，8月上旬(北京奥运会开幕式前后)是北京地区暴雨出现最为集中的时期。2）1961～2007年北京地区暴雨日数总体表现为波动式的缓慢下降，沙河暴雨日数的下降趋势最不明显，西郊居中，南苑暴雨日数的下降趋势最明显。3）暴雨日数的增减变化具有阶段性特征，1990年前南苑暴雨日数的变化与沙河、西郊有着完全相反的变化趋势。4）北京地区暴雨日数变化具有多重周期性，南苑、西郊和沙河暴雨周期日数不同。  

Analysis of the Climatic Characteristics and the Variations of the Rainstorm in Beijing Area

Using the precipitation data in Beijing during 1961－2007, statisitcs rate of the climatic tendency, polynomial curve fitting, and Morlet wavelet method, the climatic characteristics and the trends of the climatic change of rainstroms in Beijing were analysed. The results show that: 1）Rainstorm has obvious monthly variation characteristics, the first 10 days of August(before and after the Beijing Olympic Games opening ceremony)are the most evident stage of the rainstorm days in Beijing. 2）The general trend of the annual rainstorm days has slowly decreased with fluctuation in Beijing during 1961〖CD*2〗2007, the descending rate of the annual rainstorm days at Shahe station is the slightest, that at the Xijiao station is second, and that at Nanyuan station is the most marked among the three stations. 3）The variations of the incremental and reduced rainstorm days have periodic characteristics, and there are absolutely opposite variation trends at Nanyuan station before 1990, in comparison with Shahe station and Xijiao station. 4）The variations of the annual rainstorm days have multiple periodicity in Beijing. Different periodic oscillations of the annual rainstorm days exist at Nanyuan station, Shahe station, and Xijiao station.