区域降水的多时间尺度特征

Multiple-Time-Scale Features of Summer and Autumn Rainfall in Chongqing Region

简单介绍小波分析技术的特点及其在大气科学研究中的应用。用一维Morlet小波变换对重庆地区 (单站资料 ) 196 0～ 2 0 0 0年 4 1年降水资料序列作周期诊断分析 ,发现重庆市降水存在最为明显的准 18年周期振荡 ,其次也具有 11年、3～ 5年及 8年的准周期。Morlet小波变换系数的零点对应于重庆市 4 0余年降水变化的突变点 ,据此得出降水的多时间尺度特征和规律。无论是较大时间尺度 ,还是较小时间尺度 ,重庆市夏季降水、年降水变化均处于较强的偏多期 ,且偏多的趋势仍较明显 ,而秋季降水则处于较强的偏少期。

Brief introduction of wavelet analysis and its application in atmospheric science is presented and the periodicity of 41 years (1960 to 2000) in the Chongqing precipitation time series (single station data) was diagnosed by the means of one-dimension Morlet wavelet transformation. The results show that there exists an obvious quasi 18-year period oscillation in Chongqing rainfall and less pronounced periods of 11, 3-5 and 8 years. It is found that the zero points of Morlet wavelet transformation coefficients correspond with the inflexions of the 40-year precipitation variation in Chongqing, and the zero-point positions of the of Morlet wavelet transformation coefficients correspond with the positions of the abrupt change points of the precipitation variation in Chongqing. Either over a large time scale or small scale, for summer and annual precipitation variations, Chongqing was in an obviously more-than-normal period, while for autumn precipitation, in an obviously less-than-normal period.