Breaking induced turbulence generation and dissipation in simulated broadband wave fields

Wave breaking in steep ocean wave fields is the major dissipation mechanism for waves and is known to generate turbulence and mixing in the upper ocean. However, due to the complexity related to the multi-scale and nonlinear nature of wave breaking, both the generation of turbulence and dissipation are still not well understood and the parameterizations of both are largely empirical. In this follow-up study of breaking broadband wave fields using the multi-layer numerical model (Wu et al. JFM 2023), we characterize the generation of underwater turbulence and the breaking-related dissipation of the wave field. The simulations produce averaged mixing layer depth and shape similar to those previously observed, with additional dynamical features that can potentially help improve the wave-induced mixing parameterization. Dissipation is analyzed in the framework of the fifth moment of breaking front distribution, and uncertainties of the breaking strength parameter are discussed.