风浪局域小波谱峰的涨落

Fluctuations of peak energy and peak frequency of local waveletenergy spectrum for wind waves

将湍流研究中已得到有效应用的局域小波能谱概念引入到风浪研究。分析了实验室不同风速下风浪的局域小波能谱。结果表明，局域小波谱峰值存在着显著的涨落，涨落的方差随风速的增加而增大。这不仅体现了风浪的局域结构，还意味着通常风浪谱的应用中除了要考虑平均意义下的频谱峰值外，还必须考虑局域小波谱峰值的涨落方差。

This study is concerned with the physical interpretations for the statistical uncertainty of the spectral peak energy and peak frequency of the Fourier frequency spectrum. The local wavelet energy spec- trum, based on the wavelet transform, is introduced to analyze the wind wave data obtained in a wind wave channel. It is shown that wave energy exhibits localizations both in scale (frequency) and physical space (time) , which implies energy intermittency-the energy at a given frequency may not be evenly distributed in the whole time. Especially , the peak energy and the corresponding peak frequency of a local wavelet energy spectrum have significant fluctuations as time evolves. Such intermittency and fluctuations give appropriate in- terpretations for the above mentioned statistical uncertainty.