Wave‐turbulence interaction and its induced mixing in the upper ocean

In the ocean, interaction among the mean current, the surface waves, and turbulence is a major mechanism for energy transfer from surface waves to the turbulence field. This process is associated with attenuation of surface waves. This paper deals with wave‐turbulence interaction and its induced mixing using field observations and a one‐dimensional, level 2.5 turbulence closure model. The results show that both the turbulence kinetic energy dissipation rate and the vertical mixing induced by wave‐turbulence interaction are a function of u s 0 u * 2 and wave parameters, where u s 0 is the Stokes drift at the sea surface and u * is the friction velocity in water. The former decays with the depth away from the surface in the form of e 2 kz , while the latter decays as e 3 kz ( k is the wave number). We also analyze the wave decay induced by wave‐turbulence interaction. The decay time scale is in proportion to cL / u * 2 , while in inverse proportion to , where c is a phase speed, L is a wavelength, and δ is a wave steepness. A series of numerical experiments are performed to evaluate the effects of wave‐turbulence interaction. The results from the cases with effects of wave‐turbulence interaction show significant improvement in simulation of turbulence characteristics compared to the cases in the absence of surface waves. This implies that wave‐turbulence interaction is a significant mechanism for generation of turbulence kinetic energy in the upper ocean and plays an important role in regulating vertical mixing and surface wave decay.