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

The uncertainty of the high frequency tail slope of wave spectra, as a resu lt of the intrinsically random variability of wind generated waves and the estimation procedures of the wave spectra, is examined by using simulated a nd field measured wave records. It is shown that considerable uncertainty o n the 'true' value of the slope exists due to the statistical variability o f the spectral estimates. Furthermore, significant uncertainties are introd uced both by the choice of the method of spectral estimation and by varying the number of degrees of freedom. The identification of these different so urces of uncertainty and the quantification of their values in some represe ntative 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. (C) 1999 Elsevier Science Ltd. All rights r eserved.