The whitecap coverage model from breaking dissipation parametrizations of wind waves

Abstract

An analytical model for whitecap coverage has been established from wave breaking dissipation models by improving the model of Kraan et al. [1996]. The similarity of three wave breaking parametrizations has been discussed and applied to develop the analytical model. The proposed model predicts an inversely quadratic dependence of whitecap coverage on wave age, after invoking the 3/2 power law. The undetermined parameter in the model is fixed with the latest published data sets. The proposed model is more consistent with the four data sets used than the other two analytical models presented more recently, which would underestimate significantly the four data sets overall. The substantiation of the field observations to inversely quadratic dependence on wave age means that the choice for the dependence of the damping rate on wave steepness by Komen et al. [1984] in quasilinear dissipation model has some support from observations of the whitecap coverage. The limitation of the single parameter description to whitecap coverage and the controversy on the nature of the dependence of wave breaking properties on wind wave status due to the single-parameter description are discussed. It is pointed out that the multiple-parameter scheme is expected to give rise to a consistent interpretation to the variability of whitecap coverage. Copyright 2007 by the American Geophysical Union.