Uncertainty in the estimation of the slope of the high frequency tail of wave spectra

Abstract

The uncertainty of the high frequency tail slope of wave spectra, as a result of the intrinsically random variability of wind generated waves and the estimation procedures of the wave spectra, is examined by using simulated and field measured wave records. It is shown that considerable uncertainty on the ‘true’ value of the slope exists due to the statistical variability of the spectral estimates. Furthermore, significant uncertainties are introduced both by the choice of the method of spectral estimation and by varying the number of degrees of freedom. The identification of these different sources of uncertainty and the quantification of their values in some representative cases are important for the correct interpretation of results from measurements programs aiming at establishing the correct slope of the high frequency tail of wave spectra.