Parameterization of Wave-induced Mixing Using Large Eddy Simulations (LES)

The turbulent motions in thin ocean surface boundary layers (OSBL) control the exchange of momentum, heat and trace gases between the atmosphere and ocean. However, the current parametric equations of turbulent motion applied to global climate models result in systematic or substantial errors in the OSBL. Recently, significant mixing caused by surface wave processes has included as a missing aspect of these parametric equations. In this study, Large Eddy Simulations (LES) are used to investigate the ocean mixed layer structure under different ocean forcings including wave effects included as Stokes forces and parameterized wave breaking in the wave-averaged equations. To examine the effects of wave parameters on the mixing, a series of wave conditions varying wave lengths and periods are used to drive the model into a variety of Langmuir turbulence and wave breaking outcomes. Wind intensities are also varied to investigate the response of the upper layer mixing. These experiments suggests that the profile of eddy viscosity is more sensitive to the wave height than to the wave length. A new parametric relationship for the eddy viscosity in the upper layer is derived.