一种结合小波分析的EMD周期分析方法——以南宁市年降水量为例
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摘要
针对传统EMD方法中Hilbert变换未必能正确计算出本征模态函数瞬时频率这一问题,采用小波分析替代Hilbert变换来优化EMD方法,为水文时间序列的周期分析提供了一种新途径。并对南宁市1961~2015年降水量时间序列进行了周期分析。结果表明,南宁市年降水量序列经改进的EMD方法分解可得到1个趋势项和4个IMF分量。趋势项表明南宁市历年年降水量呈现出明显的下降趋势;对IMF分量进行小波分析得到了年降水量序列分别具有4~6a、10~13a、25~29a的准周期特征。
The Hilbert transform of traditional EMD method may be unable to correctly calculate the instantaneousfrequency of intrinsic mode function. In view of this problem, the Hilbert transform is substituted by wavelet analy-sis to improve the EMD method and provide a new route for periodic analysis of hydrological time series. The annualprecipitation time series of Nanning from 1961 to 2015 was analyzed with the improved EMD method, showing onetrend and four IMF components. The annual precipitation of Nanning City has a significant dropping trend. The re-sults of wavelet analysis of IMF components demonstrate the annual precipitation series have quasi-periodic charac-teristics of 4~6 a, 10~13 a and 26~29 a.
The Hilbert transform of traditional EMD method may be unable to correctly calculate the instantaneousfrequency of intrinsic mode function. In view of this problem, the Hilbert transform is substituted by wavelet analy-sis to improve the EMD method and provide a new route for periodic analysis of hydrological time series. The annualprecipitation time series of Nanning from 1961 to 2015 was analyzed with the improved EMD method, showing onetrend and four IMF components. The annual precipitation of Nanning City has a significant dropping trend. The re-sults of wavelet analysis of IMF components demonstrate the annual precipitation series have quasi-periodic charac-teristics of 4~6 a, 10~13 a and 26~29 a.
引文
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[4]林伟,谢洪,张金山.基于EMD的云南东川蒋家沟泥石流年输沙量多时间尺度分析[J].现代地质,2013,(3):733-737.
[5]章国勇,伍永刚,刘洋,等.基于EEMD与EMD的降雨序列多时间尺度对比分析[J].中国农村水利水电,2014,(8):98-103.
[6]陈旭.汾河上游径流演变特性分析及其预测方法研究[D].太原:太原理工大学,2015.
[7]任博,薛泽宇,任全志,等.基于EMD的凌河流域降水径流预测模型研究[J].人民黄河,2016,38,(6):63-65.
[8]王晓琳.基于小波分析的邯郸山区水文特性分析与预测[D].河北邯郸:河北工程大学,2012.
[9]郭高轩,辛宝东,朱琳,等.基于小波变换的北京地区1724~2009年降水量多尺度分析[J].水文,2012,32(3):29-33.
[10]刘奎建,丁志宏.基于EMD的北洛河天然年径流量变化特征分析[J].中国农村水利水电,2008,(10):36-38.
[11]李兴燕,丁志宏.汾河天然年径流量波动特征多时间尺度分析的EMD方法[J].水电能源科学,2008,26(1):30-32.
[2]Norden E Huang,Zheng Shen,Steven R Long.A NewView of Nonlinear Water Waves:The Hilbert Spectrum[J].AnnRev Fluid Mech,1999,(31):417-457.
[3]任健,史红玲.黄河下游年径流量及输沙量变化的EMD分析[J].人民黄河,2012,34(8):33-35.
[4]林伟,谢洪,张金山.基于EMD的云南东川蒋家沟泥石流年输沙量多时间尺度分析[J].现代地质,2013,(3):733-737.
[5]章国勇,伍永刚,刘洋,等.基于EEMD与EMD的降雨序列多时间尺度对比分析[J].中国农村水利水电,2014,(8):98-103.
[6]陈旭.汾河上游径流演变特性分析及其预测方法研究[D].太原:太原理工大学,2015.
[7]任博,薛泽宇,任全志,等.基于EMD的凌河流域降水径流预测模型研究[J].人民黄河,2016,38,(6):63-65.
[8]王晓琳.基于小波分析的邯郸山区水文特性分析与预测[D].河北邯郸:河北工程大学,2012.
[9]郭高轩,辛宝东,朱琳,等.基于小波变换的北京地区1724~2009年降水量多尺度分析[J].水文,2012,32(3):29-33.
[10]刘奎建,丁志宏.基于EMD的北洛河天然年径流量变化特征分析[J].中国农村水利水电,2008,(10):36-38.
[11]李兴燕,丁志宏.汾河天然年径流量波动特征多时间尺度分析的EMD方法[J].水电能源科学,2008,26(1):30-32.