Turbulence Production by Nonbreaking Waves

Introduction: Historically, the parameterization of turbulence production in the upper ocean has relied primarily on the assumptions of near-wall turbulence theory, in which the wind-generated surface friction velocity acts as a moving boundary. In more complete parameterizations, an additional term is added in the top few meters to account for the dissipation of breaking surface waves. These two mechanisms are responsible for the bulk of the produced turbulence. However, there exists a distinct third mechanism, first described by Phillips,1 in which turbulence is produced due to turbulence interaction with nonbreaking waves. For decades, the contribution of this mechanism was considered relatively small and was therefore largely neglected in practical applications. However, recent studies suggest otherwise. For example, Ardhuin and Jenkins2 demonstrated that long swell waves propagating across the Pacific Ocean dissipate a significant portion of their energy due to wave–turbulence interaction. These findings motivated the present work, in which a series of laboratory and numerical investigations were conducted to explore this phenomenon. Quantitative results of this study provide a validation source and enable improvements of wave dissipation parameterization, which is needed for accurate marine weather and wave forecasting.