Distribution of Surface Wave Breaking Fronts

Leonel Romero, University of California Santa Barbara, Earth Research Institute, Santa Barbara, CA, United States
This study describes a model of Phillips' Λ(c) distribution, which is the expected length of breaking fronts (per unit surface area) moving with velocity c to c+dc, providing a framework for coupled atmosphere-wave-ocean models to explicitly account for wave breaking related air-sea fluxes including energy, momentum, gas and aerosols. The model of Λ(c) depends on the spectral saturation, based on the statistics of the lengths of crest exceeding wave slope criteria, including long wave-short wave modulation. A wave breaking dissipation function based on Λ(c) was implemented in the model WaveWatchIII. The wave solutions are consistent with the observations, including several metrics of the spectrum and Λ(c) distributions. The whitecap coverage derived from Λ(c) reproduces recent parameterizations over a wide range of wind speeds including high winds. The wave breaking variability due to wave-current interaction is significant at submesoscales (order 1 km or smaller). The wave breaking model can be further developed to model gas transfer coefficients and aerosol production.