Coherent gust detection by wavelet transform

The spectrum is commonly used to characterize the energy content and the longitudinal scale of turbulence in the wind field. However, this incoherent signal model is not always sufficient to identify intermittent coherent structures in the wind that may be responsible for wind damage. These periods of gusts may be viewed as coherent structures occurring in an otherwise incoherent signal. In this paper, we describe a method for using wavelet transforms to detect coherent structures in the wind field. To detect coherent gusts, we use the Haar wavelet since the Haar analyzing function detects the magnitude and length scale of sustained changes in signal level. A statistical technique is developed to separate coherent structures in the wavelet transform from fluctuations due to incoherent noise. (C) 1998 Elsevier Science Ltd. All rights reserved.