The form of the asymptotic depth-limited wind wave frequency spectrum

This paper presents a comprehensive set of field experiments investigating the form of the asymptotic, depth-limited wind wave frequency spectrum. Such a spectrum represents the upper limit to growth from active wind forcing in finite depth conditions. The data clearly define asymptotic limits for the nondimensional energy and nondimensional wave number as functions of nondimensional water depth. In contrast to deep water spectra, the asymptotic depth-limited form has a harmonic at a frequency slightly less than twice the spectral peak frequency. A parametric form is proposed for the spectral form, and clear functional relationships are found for all the spectral parameters. These relationships mean that the full asymptotic, depth-limited spectrum can be determined with knowledge of only the water depth and wind speed.