小波分析方法在月降水量多时间尺度分析中的应用

Application of Wavelet Analysis in Multiple Time Scale Analysis of Monthly Precipitation

为了研究查哈阳灌区月降水量在时域中存在的多层次时间尺度结构和局部化特征,运用小波分析理论,采用Mexican Hat小波函数对降水量序列进行小波变换,进而分析其多时间尺度特性,揭示降水量在不同时间尺度下的小波变换时频特征及其丰枯交替变化的周期规律。研究结果表明,从80~120个月的较大尺度来看,灌区的月降水量可能存在30年左右的周期变化,且未来5年将仍处于偏少期;随着尺度的减小,则表现出突变点增多、周期变小的现象,且降水量很快就会从偏少期转为偏多期。

In order to study the multi-level time scale structure and localized characteristics of monthly precipitation in Chahayang irrigation district in time region,the wavelet analysis theory is adapted.This paper carries out wavelet transform through Mexican Hat wavelet function and analyzes the multiple time scale characteristics of precipitation,and then reveals the wavelet transform time-frequency features of precipitation at different time scales and interchanged periodic law between the rainfall period and the rainless period.The results show that from the larger scale of 80~120 months,there may be about 30 year periodic variation in the monthly precipitation of irrigation district,and furthermore,it will be still in the low period in the next five years.However,with the reduction of scale,the catastrophe points will increase and the cycle will become small,and furthermore,the precipitation will change quickly from the low period to the high period.