The response of wind-wave spectra to changing winds. Part I: increasing winds.

Abstract

Continuous time series of wind profiles and wind waves under growing conditions were analysed for a study of the response of one dimensional wind wave frequency spectra to unsteady rinsing winds. The factor in the equilibrium range spectral equation shows remarkable fluctuation. It becomes smaller for increasing wind conditions (i.e. increasing factor velocity) and larger for decreasing wind conditions within a range of (5-9) x 10-2. The slope of the spectra is very close to the (angular frequency)-4 generally, but has a tendency to be slightly steeper for decreasing winds. The response observed suggests that the processes of the adjustment of the wind wave field involve both upward and downward cascading of the wave energy.