风浪局域小波谱峰的涨落

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着的涨落,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.

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

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.