基于小波方法的西安市年降水量多时间尺度特征分析

Multiple Time Scale Characteristics Analysis of Annual Precipitation in Xi'an City Based on Wavelet Method

小波分析具有时频局部化特征,可清晰地给出各种时间尺度周期的强弱分布以及降水量偏多、偏少的变化趋势。应用小波分析的方法,对西安市1951～2006年共56年的年降水量序列进行多时间尺度特征分析。结果表明,西安市年降水量序列在整个时间域内主要受2～6年、6～12年、16～34年时间尺度波动变化影响,不同时间尺度下,降水量偏多、偏少交替变化不相同。年降水量序列主要存在4年、8年、26年左右的主周期,其中,26年为第一主周期。另外,西安市多年降水量呈弱下降趋势,2006年以后的降水应呈正位相,降水量偏多,大约到2018年左右,年降水量总体上都应当偏多。

The wavelet analysis method has the time-frequency localization characteristic,which can be clearly shown the strength distribution for kinds of time scale periods,and the variation trend for the precipitation on high side or low side.In the paper,the multiple time scale characteristics of the annual precipitation in Xi'an city from 1951 to 2006 were discussed based on wavelet analysis method.The result shows that the annual precipitation series in the entire time domain mainly be influenced by the period of the 2 to 6 years,6 to 12 years and 16 to 34 years time scale fluctuations.In different time scales,the alternated change were different in the situation that the precipitation on the high side and low side.The annual precipitation series have the main period of 4 years,8 years and 26 years,and the period of 26 years was the first main period.In addition,The annual precipitation in Xi'an city was presented a weak downward trend.The precipitation after 2006 should be a positive phase,above the average rainfall,the annual precipitation should be above average in overall until 2018.