ON BREAKING WAVE-ENHANCED TURBULENCE IN THE OCEANIC SURFACE BOUNDARY
LAYER
A coupled model of air-wave-sea interaction is used in a study of surface breaking wave-enhanced turbulence in the oceanic surface boundary layer (OSBL). Breaking waves are considered as another source of turbulent energy in the OSBL besides shear-related turbulent energy. The turbulent dissipation (epsilon) at the ocean surface is written in the form of a linear combination of terms representing shear and wave-related dissipation. The epsilon from breaking waves is estimated by using similarity theory, observational data, and wave breaking conditions of the linear theory. It is then expressed in terms of wave parameters such as wave height, phase speed, and length. The atmospheric part of the coupled model is used only to obtain correct conditions at the air-sea interface. In the model, the aerodynamic roughnesses from above and below (air/seawater sides of the wave layer), taking wave effects into account, are considered as internal parameters of the air-sea system.
Numerical experiments with various large scale winds, diffusivities, and wave ages are performed to study the breaking wave-enhanced turbulence, air-sea interaction, and OSBL characteristics under breaking wave conditions. The comparisons of the model outputs with available observational data are an important part of the study. Comparisons of the model outputs of the ocean turbulent dissipation distribution, aerodynamic roughness length, and drag coefficient with all available observational data are made in this study.