Abstract: The Yellow River Basin is located in the arid and semi - arid region in the north of China, where is less river runoff and precipitation is the basis source of water resources , the basin is with seriously scarce water resources in China, even less in the world. Based on the monthly and annual rainfall data from 1961 to 2000 of 97 weather stations, the spatial structure and changes of rainfall and the multi-time scales characteristics of seasonal and annual rainfall in the past 40 a in the Yellow River Basin had been analyzed using Mexican Hat wavelet analysis in this report. The periodic oscillation of rainfall variation and the points of abrupt change at different time scales along the time series are discovered and the main periods of every serial are confirmed. It was showed that the distribution of rainfall in the Yellow River Basin had obviously regional difference, which was influenced not only by the weather system but also by the geographical environment such as topography, etc; there are obvious periodic oscillation of 8-12 a and 4-6 a for the seasonal and annual rainfalls variation. The variation trend of the summer rainfall is similar in some degree with that of the annual rainfall and both of them have the comparable main periods. The localization characteristics of time - frequency for wavelet analysis can demonstrate the detailed structures of rainfall. The wavelet analysis can be an alternative approach to analyze climate multi-time scales characteristics and forecast short-term climate variations.

Key words: rainfall, variation, wavelet analysis, Yellow River Basin

摘要： 采用1961—2000年黄河流域97个气象站点的系列资料，在分析黄河流域降水空间变化格局的基础上，采用墨西哥帽小波函数，对黄河流域近40 a来降水的季节变化和年际变化时间序列进行了小波分析，揭示了黄河流域降水变化的多时间尺度的复杂结构，分析了不同时间尺度下降水序列变化的周期和突变点，并确定了各序列中存在的主要周期。结果表明：黄河流域多年平均降水量的地区分布既受天气系统的制约，又受地形等地理环境的影响，造成明显的地区性差异；黄河流域年降水和各季节降水均存在8~12 a左右时间尺度的多少交替，表现出明显的周期特征，其次4~6 a左右时间尺度的周期特征也较明显，夏季降水和年降水变化趋势具有较大相似性，不同时间尺度的周期特征之间有不同程度的吻合，说明夏季降水较大程度地控制着年降水。小波分析的时频局部化特性可展现降水时间序列的精细结构，为分析气候多时间尺度变化特征及短期气候预测等节水关键问题研究提供了一种新途径。

关键词: 降水, 变化, 小波分析, 黄河流域