| The ocean surface mixed layer plays an important role in the processes of the exchange of heat and momentum between the upper ocean and the atmosphere. The effect of wind waves on the dynamical and thermal structure of the ocean mixed layer is significant.Previous work on ocean mixed layer and about the effect of wave breaking on the mixed layer structure are first summarized. Then the effects are studied using numerical models.The understanding of the effects of atmospheric forcings, including mainly the surface wind stress, net heat flux and buoyant flux, on the dynamical and thermal structure of the ocean surface mixed layer necessitates a proper knowledge of the mechanisms and influences of the different turbulent mixing processes involved in the upper ocean. A brief description of the physical mechanism of the turbulence production and its transform with the other forms of the energy is given.The global climatological monthly mean data of the mixed layer depth (MLD) supplied by Levitus (1994) in NODC based on three different criteria, are used to analyze the space distribution and seasonal variability of MLD. It is found that MLD based on a temperature change from the ocean surface of 0.5 degree Celsius is deeper, especially from Jan. to Apr., while MLD based on a variable density change from the ocean surface with a temperature change of 0.5 degree Celsius is shallower. However, the space distribution and seasonal variability of MLD obtained from different criteria are consistent with each other. In general, MLD becomes shallower and less than 50 meters with solar radiation intensifying and wind stress weakening in summer, and becomes deeper in winter, especially in oceans (such as the northwest Pacific, the north Atlantic and the Southern Ocean), where the MLD's are between 100 and 300 meters (the deepest depth being 600 m) and have evident seasonal variability. The MLD of the ocean near the Equator from 10?S to 10?N are less than 50 m and have no evident seasonal variability.We analyze the energy balance equations for mean flow, turbulence and wave motion in the ocean surface mixed layer, and discuss the wave-turbulence interaction involved. The observed phenomena, in which vertical turbulence mixing and turbulence dissipation are enhanced by the action of breaking wave, are explained.However, there are some inextricable problems in the theories of both wind waves and turbulence, so our theoretical analysis about the wave-turbulence interaction is rudimentary and incomplete. Furthermore, because of the scarcity of measurements and data, our work has to be limited to investigating the effect of wave breaking on the ocean surface mixed layer by the numerical models.A one-dimensional oceanic mixed layer model with the M-Y level-2.5 turbulence closure schemes is employed. The rate of energy loss by breaking waves is estimated by parameterization and incorporated into the model as a source of turbulence kinetic energy (TKE) by modifying the existing surface boundary condition of TKE equation. The velocity field and turbulence energy budget are calculated under different forcing conditions (The results given below are for a wind speed of 20 m/s.). When the effect of surface wave breaking is considered, MLD is 50 cm deeper than that obtained without wave breaking, and with the enhancement of wind stress forcing, the deepening of MLD is increased. When the temperature is uniform within the mixed layer, a thermocline appears at the bottom of this layer, and when the effect of surface wave breaking is considered, the temperature is 0.013 癈 lower than the result without wave breaking.On the other hand, it is indicated that the velocity field consists of a depth-independent inertial oscillation and a time-mean shear flow, which can be obtained by subtracting the inertial oscillations time mean in one inertial period. The hodograph of the velocity vector of time-mean flow at the different depths consists of a Ekman spiral, and the surface velocity is 30.3?to the right of the wind. When the...
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