东北地区近百年降水时间序列变化规律的小波分析

A wavelet analysis of the precipitation time series in Northeast China during the last 100 years

利用1905～2005年东北地区哈尔滨、长春、沈阳和大连的降水时间序列资料,采用距平和Morlet小波分析方法,研究了东北地区降水变化的多时间尺度的周期性性变化规律,并对东北地区近期降水状况进行了预测。结果表明:近百年来东北地区年降水量呈现较显著下降趋势,整个东北地区降幅为-5.2mm/10a;长春为-12.7mm/10a;哈尔滨为-7.1mm/10a;大连为-2.7mm/10a;沈阳略为上升趋势为1.3mm/10a。东北地区的年降水量存在着区域性的多重时间尺度下的周期变化特征,2a～3a、5a～6a,10a和50a左右的长期振荡周期具有全域性;长春、哈尔滨年降水的主要控制周期是20a左右;5a～6a的短周期和50年的长周期变化也对年降水有较大影响。

In recent 100 years,global warming is increasing remarkably,and there are even greater uncertainty,changing precipitation trend and regional differences.In this study,a wavelet analysis method of Morlet is used to research the periodical regulations at different time scales of the precipitation time series during the latest nearly 100 years in Northeast China.Based on the monthly and annual precipitation data of Harbin,Shenyang,Changchun and Dalian weather stations covering the period from 1905 to 2005,the periodic oscillation of precipitation 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.The result shows that the precipitation of Northeast China has a decreasing trend,with rates of-5.2mm/10a,and-12.7mm/10a,-7.1mm/10a,-2.7mm/10a,1.3mm/10a for Northeast China,Changchun,Harbin,Dalian and Shenyang respectively.There are multi-time scales of periodical change,which present appears different traits at different phases.There are periodic oscillations of 2a-3a,5a-6a,10a and 50a for the seasonal and annual precipitation variations.The local characteristics of time-frequency for wavelet analysis can demonstrate the detailed structures of precipitation.The wavelet analysis can be an alternative approach to the analysis of climate multi-time scales characteristics and the forecast of short-term climate variations.