Frequency‐Direction Spectra of Wind‐Generated Gravity Waves

Abstract

Abstract The frequency‐direction spectra of wind‐generated surface gravity waves are summarized in terms of the spectral peak frequency and the stage of wave development (ratio of wind speed at 10 m height to wave phase speed at the spectral peak frequency). The spectra exhibit an enhanced peak, an equilibrium range at frequencies higher than twice the peak, and increased directional spreading at lower and higher frequencies than the peak. Five parameters completely describe the spectra: four are functions of the stage of wave development and the fifth depends on relative (to the peak) frequency. The spectral formulae provided apply in intermediate and deep water. Marine and offshore engineers will find the formulae useful for design and operational calculations. They require only the wind vector and the spectral peak frequency as input.