基于小波分析的西昌市降水时间序列变化特征

Variation Character of Xichang City's Precipitation Time Series Based on Wavelet Analysis

利用1951～2008年西昌市降水资料,采用回归分析和Morlet小波分析方法,研究了西昌市季节、年降水量变化的多时间尺度的周期性变化规律,并对西昌市中短期降水状况进行了预测。结果表明,近58年来西昌市年降水量呈下降趋势,降幅为-2.300mm/10年;各季节有增有减,春、秋季变幅较大,春季增幅为5.711mm/10年,秋季降幅为-9.635mm/10年;夏、冬季节波动不大。季节、年降水量存在着多重时间尺度下的周期变化特征,多重时间周期尺度相互嵌套,春季的主要振荡周期为4和35年,夏季为3、15和42年,秋季为3、7、11和18年,冬季为4和15年,年降水量为3、7、15和22年。不同时间尺度,具体年份对应的相位不同,降水变化趋势的预测结果也不同。

Based on the rainfall data of Xichang City from 1951 to 2008,linear regression analysis method and wavelet analysis method of Morlet were used to analyze seasonal and annual periodical regulations at different time scales of the precipitation time series during the latest 58 years in Xichang City. We also predicted the precipitation of Xichang City in short and medium period. The results showed that in recent 58 years the precipitation of Xichang City has a decreasing trend,with rates of-2.300 mm/10 Year. Different seasons have different amplitude,with the rates increasing 5.711 mm/10 Year in spring,while decreasing 9.635 mm/10 Year in autumn,but the rate fluctuates slightly in other seasons. The seasonal and annual precipitation present the character of periodical regulations at different time scales of the precipitation time series,and multiple time series nest one another. The oscillator period for each season is 4 35 years in spring,3,15 42 years in summer,3,7,11 and 18 years in autumn,4,15 years in winter,3,7,15 and 22 years for annual precipitation. The predicting results of precipitation changing depends not only on different time series but also on the phase of specific years.