中文摘要：

本文介绍了用频谱分析法进行降水量分析和预报的基本方法。首先对实测序列进行趋势项分析；其次用自相关函数进行谐波模式检验；然后根据函数的傅立叶级数展开理论，分析谱参数之间的函数关系，计算傅氏系数；最后采用F分布检验法对周期进行显著性检验。确定主要周期，从而建立预报模型。并应用该方法对挠力河流域菜咀子站的年降水量进行了预报，结果表明该区年降水量存在两个主要周期（3年和9年左右），反映了该地区的气候变化规律。实例证明，频谱分析法预测效果很好．预报结果可为挠力河流域的水资源开发和管理提供依据。

英文摘要：

This paper introduced a method of forecasting precipitation with frequency spectrum analysis. With the method, tendency of measured value was analyzed, harmonic mode was checked by using autocorrelation function, the relation between spectrum parameters was analyzed and Fourier coefficient was calculated based on the theory of Fourier series. Finally, the significance of every period was tested and dominant period determined so as to establish the prediction model. The method has been used to forecast the annual precipitation in the Naolihe River Basin, The results show that it has two dominant periods, namely three years and nine to ten years, which reflect the regularity of climate change in the area. The practice indicates that the forecasting effect of spectrum analysis method is very good, which could provide basis for the development and management of water resources in the Naolihe River Basin.