Decomposition of wind velocity and temperature fluctuations into wave and turbulent signals, using wavelet transform

Nisia Krusche, Osvaldo Luis Leal de Moraes, Birajara S. Machado


In the stable stratified atmospheric boundary layer, spectra might be affected by several kinds of waves. Since the problem of turbulent diffusion is closely related to the spectra of wind velocity fluctuations, it is necessary to separate the contributions of those waves from that of turbulence. Discrete wavelet packets transform was applied to temperature and vertical velocity fluctuations measured in Candiota, RS (31°28´ S, 53°40´ W), sampled with a frequency of 10 Hz and 1 Hz. In these datasets, waves have been detected through cospectral techniques. Wavelet transform was used to decompose the series. It allowed identification of those contributions that are related to the detected waves, which were then removed from the original signals. Therefore, this method may be used to decompose the series in two signals, one containing waves and other corresponding to random turbulence of the flow.

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