【摘要】 利用甘肃河东建站最早的 9个代表站的年降水量资料 ,采用谐波分析和小波分析方法 ,计算了年降水量序列各种时间尺度的周期 ,以及 1 0a和 2 0a相空间时间序列的 2～1 0a周期试验。结果表明 :甘肃中部地区年降水量总体仍以准 3a周期最为显著 ;陇东表现为 9a周期 ;陇南无明显周期。相空间序列的周期试验显示 ,甘肃中部的准 3a周期主要反映在 50～ 70年代 ,近 2 0～ 30a则以 8～ 9a周期较为明显 ;陇东近 1 0a主要表现为准 2a振荡。进一步的分析表明 ,甘肃中部年降水量的准 3a周期振荡目前处于历史最低谷 ,但其存在 1 9a和 2 8a以上的两种长周期变化 ,可能在 2 0 0 5年左右恢复到显著水平。 9a周期表现出明显的2 3a的韵律 ,目前振幅虽然在起作用 ,但未来可能进入相对弱的时期。更多还原

【Abstract】 Nine stations annual precipitation data of east Gansu have been used by means of harmonic analysis and wavelet analysis. From 2 to N/2 years period were calculated and from 2 to 10 years period were experimented in phase space of 10 years and 20 years time sequence. It is shown that the significance level of quasi 3 years period of annual precipitation is the best in central Gansu. East Gansu has 9 years period, south Gansu has not signal period. The period experiment of phase space shown, the quasi 3 years period of annual precipitation of central Gansu is mainly in from 1950’s to 1970’s, the quasi 9 years period is signally in last 20 to 30 years. the quasi 2 years period oscillation of East Gansu is the mainly in last 10 years. Make further analysis for quasi 3 years period of annual precipitation of central Gansu at the lower point now in the past records, but it has 19 years and over 28 years long period. Maybe it can be return to the significance level in 2000’s. The 9 years period shows 23 years rhythm clearly now, but maybe it go into a relatively weak in the coming.更多还原