In this study, the Hilbert-Huang transform was applied to experimental measurements performed in a wind tunnel to determine the frequency of occurrence of the spectral maximum. These maximum frequencies are associated with the time scale of the most energetic eddies and represent an important input parameter in the pollutants dispersion models. The values of the maximum frequencies obtained by the Hilbert-Huang marginal spectrum are compared with the vaues obtained by the traditionally used
Fourier transform. The results show that the energy distribution calculated by both methods are very similar in the region of occurence of the spectral maximum, and for this reason, the maximum frequency values obtained by each method do not presente significant differences. Under determined hypothesis, the Hilbert-Huang transform provided physically more realistic maximum frequency values that those obtained using the Fourier transform
