The coupled ocean–atmosphere–wave–sediment transport (COAWST) modeling system is employed to investigate the role of wave-mixing playing in the upwelling off the west coast of Hainan Island (WHU). Waves, tides and sea surface temperature (SST) are reproduced reasonably well by the model when validated by observations. Model results suggest the WHU is tidally driven. Further investigations indicate that inclusion of wave-mixing promotes the intensity of the WHU, making the simulated SST become more consistent with remote-sensed ones. Dynamically, wave-mixing facilitates the “outcrop” of more upwelled cold water, triggering stronger WHU and leading to a three-dimensional dynamical adjustment. From the perspective of time, wave-mixing contributes to establishing an earlier tidal mixing front strong enough to generate WHU and that is, WHU may occur earlier when taking wave-mixing into consideration.

Three dimensional wave-induced mixing plays an important role in shallow water area. A quite direct approach through the Reynolds average upon characteristic length scale is proposed to parameterize the horizontal and vertical shallow water mixing. Comparison of finite depth case with infinite depth results indicates that the difference of the wave-induced mixing strength is evident. In the shallow water condition, the infinite water depth approximation overestimates the mixing strength in the lower layers. The nonzero horizontal wave-induced mixing presents anisotropic property near the shore. The Prandtl's mixing length theory underestimated the wave-induced mixing in the previous studies.

The significant underestimation of sea surface temperature (SST) and the temperature in the upper ocean is one of common problems in present climate models.The influence of the wave-induced mixing on SST and the temperature in the upper ocean was examined based on a global climate model.The results from the model coupled with wave-induced mixing showed a significant improvement in the simulation of SST and the temperature in the upper ocean compared with those of the original model without wave effects.Although there has still a cold bias, the new simulation is much closer to the climatology, especially in the northern ocean and tropical ocean.This study indicates that some important physical processes in the accurate simulation of the ocean may be ignored in present climate models, and the wave-induced mixing is one of those factors.Thus, the wave-induced mixing (or the effect of surface waves) should be incorporated properly into climate models in order to simulate or forecast the ocean, then climate system, more accurately.

The previous studies by the MASNUM research team have shown the effectiveness of the waveinduced mixing (Bv) in improving the simulation of upper-ocean thermal structure. The mechanisms of Bv are further investigated by incorporating different Bv products into the MASNUM wave-circulation coupled model. First, experiments were designed to explore the effects of Bv, which contain the contributions at different wave lengths (l). The results of three experiments, the non-Bv case, the short-wave case (l <300 m), and the long-wave case (l >300 m) are compared, and it is found that the long waves are the most important component for Bv to generate mixing in the upper ocean. As the swell plays dominant role in mixing, the parameterization of Bv into wind may be not a proper way. Second, Bv effects at different time-scales, including daily and monthly, were examined. The results show that the monthly averaged Bv has larger impact than the daily averaged Bv, especially in summer.

The influence of the nonbreaking surface wave-induced mixing under the mixed layer on the oceanic circulation was investigated using an isopycnal-coordinate oceanic circulation model. The effect of the waveinduced mixing within the mixed layer was eliminated via a bulk mixed layer model. The results show that the wave-induced mixing can penetrate through the mixed layer and into the oceanic interior. The waveinduced mixing under the mixed layer has an important effect on the distribution of temperature of the upper ocean at middle and high latitudes in summer, especially the structure of the seasonal thermocline. Moreover, the wave-induced mixing can affect the oceanic circulation, such as western boundary currents and the North Equatorial Currents through changes of sea surface height associated with the variation of the thermal structure of the upper ocean.

Based on the theoretical spectral model of inertial internal wave breaking (fine structure) proposed previously, in which the effects of the horizontal Coriolis frequency component f-tilde on a potential isopycnal are taken into account, a parameterization scheme of vertical mixing in the stably stratified interior below the surface mixed layer in the ocean general circulation model (OGCM) is put forward preliminarily in this paper. Besides turbulence, the impact of sub-mesoscale oceanic processes (including inertial internal wave breaking product) on oceanic interior mixing is emphasized. We suggest that adding the inertial internal wave breaking mixing scheme (F-scheme for short) put forward in this paper to the turbulence mixing scheme of Canuto et al. (T-scheme for short) in the OGCM, except the region from 15°S to 15°N. The numerical results of F-scheme by using WOA09 data and an OGCM (LICOM, LASG/IAP climate system ocean model) over the global ocean are given. A notable improvement in the simulation of salinity and temperature over the global ocean is attained by using T-scheme adding F-scheme, especially in the mid- and high-latitude regions in the simulation of the intermediate water and deep water. We conjecture that the inertial internal wave breaking mixing and inertial forcing of wind might be one of important mechanisms maintaining the ventilation process. The modeling strength of the Atlantic meridional overturning circulation (AMOC) by using T-scheme adding F-scheme may be more reasonable than that by using T-scheme alone, though the physical processes need to be further studied, and the overflow parameterization needs to be incorporated. A shortcoming in F-scheme is that in this paper the error of simulated salinity and temperature by using T-scheme adding F-scheme is larger than that by using T-scheme alone in the subsurface layer.

Based on the quasi-geostrophic vorticity equation,the present paper simulates the water mixing process in the formation of ocean shear waves using large eddy simulation methods.From Lagrangian tracing,we study the ocean shear wave's changing from wave character to vortex character.The distance between tracer groups increases near the ocean shear wave area,and decreases between ocean shear waves.The tracers that are uniformally distributed in space do not retain the uniform character in the mixing process.The frequency shift of the perturbation waves is caused by their nonlinear interaction.The wave number ratio and phase lag of the initial perturbation waves effect the mixing process,but the results show tittle difference.The increase of the visrnsity coefficient will restrain the mixing process.

A new three-dimensional numerical model is derived through a wave average on the primitive N-S equations, in which both the "Coriolis-Stokes forcing" and the "Stokes-Vortex force" are considered. Three ideal experiments are run using the new model applied to the Princeton ocean model (POM). Numerical results show that surface waves play an important role on the mixing of the upper ocean. The mixed layer is enhanced when wave effect is considered in conjunction with small Langmuir numbers. Both surface wave breaking and Stokes production can strengthen the turbulent mixing near the surface. However, the influence of wave breaking is limited to a thin layer, but Stokes drift can affect the whole mixed layer. Furthermore, the vertical mixing coefficients clearly rise in the mixed layer, and the upper ocean mixed layer is deepened especially in the Antarctic Circumpolar Current when the model is applied to global simulations. It indicates that the surface gravity waves are indispensable in enhancing the mixing in the upper ocean, and should be accounted for in ocean general circulation models.

Stokes drift is the main source of vertical vorticity in the ocean mixed layer.In the ways of Coriolis-Stokes forcing and Langmuir circulations, Stokes drift can substantially affect the whole mixed layer.A modified Mellor-Yamada 2.5 level turbulence closure model is used to parameterize its effect on upper ocean mixing conventionally.Results show that comparing surface heating with wave breaking, Stokes drift plays the most important role in the entire ocean mixed layer, especially in the subsurface layer.As expected, Stokes drift elevates both the dissipation rate and the turbulence energy in the upper ocean mixing.Also, influence of the surface heating, wave breaking and wind speed on Stokes drift is investigated respectively.Research shows that it is significant and important to assessing the Stokes drift into ocean mixed layer studying.The laboratory observations are supporting numerical experiments quantitatively.

In order to understand the mixing process of saline and fresh water at the estuary of the Zhujiang River (Lingdingyang Bay), the Zhujiang River Conservancy Commission made several field observations from 1978 to 1979. The resulting data indicate that the mixing process is quite unique and complicated. Here demonstrations are made from different angles so as to show the nature of the process.
On the whole, the Zhujiang Estuary can be roughly regarded as a vertical partly-mixed type with a lateral salinity gradient.