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.

Turbulent mixing in the upper ocean (30-200 m) of the northwestern Weddell Sea is investigated based on profiles of temperature, salinity and microstructure data obtained during February 2014. Vertical thermohaline structures are distinct due to geographic features and sea ice distribution, resulting in that turbulent dissipation rates (ε) and turbulent diffusivity (K) are vertically and spatially non-uniform. On the shelf north of Antarctic Peninsula and Philip Ridge, with a relatively homogeneous vertical structure of temperature and salinity through the entire water column in the upper 200 m, both ε and K show significantly enhanced values in the order of O(10^-7)-O(10^-6) W/kg and O(10^-3)-O(10^-2) m²/s respectively, about two or three orders of magnitude higher than those in the open ocean. Mixing intensities tend to be mild due to strong stratification in the Powell Basin and South Orkney Plateau, where ε decreases with depth from O(10^-8) to O(10^-9) W/kg, while K changes vertically in an inverse direction relative to ε from O(10^-6) to O(10^-5) m²/s. In the marginal ice zone, K is vertically stable with the order of 10-4 m²/s although both intense dissipation and strong stratification occur at depth of 50-100 m below a cold freshened mixed layer. Though previous studies indentify wind work and tides as the primary energy sources for turbulent mixing in coastal regions, our results indicate weak relationship between K and wind stress or tidal kinetic energy. Instead, intensified mixing occurs with large bottom roughness, demonstrating that only when internal waves generated by wind and tide impinge on steep topography can the energy dissipate to support mixing. In addition, geostrophic current flowing out of the Weddell Sea through the gap west of Philip Passage is another energy source contributing to the local intense mixing.

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.

The turbulent mixing in the upwelling region east of Hainan Island in the South China Sea is analyzed based on in situ microstructure observations made in July 2012. During the observation, strong upwelling appears in the coastal waters, which are 3℃ cooler than the offshore waters and have a salinity 1.0 greater than that of the offshore waters. The magnitude of the dissipation rate of turbulent kinetic energy ε in the upwelling region is O (10^-9 W/kg), which is comparable to the general oceanic dissipation. The inferred eddy diffusivity K_ρ is O (10^-6 m²/s), which is one order of magnitude lower than that in the open ocean. The values are elevated to K_ρ≈O (10^-4 m²/s) near the boundaries. Weak mixing in the upwelling region is consistent with weak instability as a result of moderate shears versus strong stratifications by the joint influence of surface heating and upwelling of cold water. The validity of two fine-scale structure mixing parameterization models are tested by comparison with the observed dissipation rates. The results indicate that the model developed by MacKinnon and Gregg in 2003 provides relatively better estimates with magnitudes close to the observations. Mixing parameterization models need to be further improved in the coastal upwelling region.

South China Sea, its circulation and connection with other parts of the world oceans, poses important scientific questions. From the prospective view, we postulate ten key research directions to be pursued in the coming future, including ventilation of a monsoon dominated sea, water mass formation/transformation, heat/salt and water mass balance, energetics and mixing, mesoscale eddies, the role of typhoon, deep circulation and paleoclimate records, interaction with adjacent oceans, upwelling and ecology system, and response to climate changes.

The Jiaojiang Estuary is shallow,macro-tidal dominated and extremely turbid,with a larger variation of the freshwater discharge.The estuarine stratification and classification are analysed by using a set of field data observed in wet season.
In spring tide,the depth-mean peak tidal currents can reach 2 m/s.During flood tide the water column is vertitally homogeneous,but the horizontal salinity gradient is large and there is a fresh water front.A 1 m thick fluid mud layer capped by lutocline is formed when the tidal current is less than 0.3 m/s.As the low-salinity trapped in the fluid mud layer,underlying saltier water enhances vertical mixing when the fluid mud layer is eroded and the water column is only slightly stratified during ebb tide.

Four cruises were conducted during 2002-2003 in the Changjiang Estuary and adjacent coastal areas. The data presented show a clear coast to open sea gradient in nutrients related to the river inputs. Maximum values of chlorophyll a were typically observed at intermediate salinities at surface water and coincided with non-conservative decreases in nutrients along the salinity gradient, indicating that removal of nutrients was related to phytoplankton uptake. The seasonal variations of nutrient concentrations were just opposite to those of chlorophyll a, indicating that the seasonal variations of nutrients were mainly controlled by phytoplankton uptake, whereas riverine inputs merely weakened or balanced its extent. During the estuarine mixing, phosphate demonstrated some remobilization during all the four cruises; whereas both conservative and non-conservative behaviors for dissolved inorganic nitrogen and silicate were observed in the study area, indicating that both biotic and abiotic events may affect their behaviors during the estuarine mixing. Under the influence of freshwater inputs with high value of ratio of nitrogen to phosphorus, the estuarine and coastal waters impacted by the Changjiang plume were high (> 30) in ratio of nitrogen to phosphorus, but rates of primary production were apparently not constrained by any kind of nutrient elements. However, the low (< 1) ratio of silicate to nitrogen in most of the study area might be linked with the rapidly increasing frequency of harmful algal bloom(HAB) incidents in recent years in the coastal waters impacted by the Changjiang plume.

The effects of biological heating on the upper-ocean temperature of the global ocean are investigated using two ocean-only experiments forced by prescribed atmospheric fields during 1990–2007, on with fixed constant chlorophyll concentration, and the other with seasonally varying chlorophyll concentration. Although the existence of high chlorophyll concentrations can trap solar radiation in the upper layer and warm the surface, cooling sea surface temperature (SST) can be seen in some regions and seasons. Seventeen regions are selected and classified according to their dynamic processes, and the cooling mechanisms are investigated through heat budget analysis. The chlorophyll-induced SST variation is dependent on the variation in chlorophyll concentration and net surface heat flux and on such dynamic ocean processes as mixing, upwelling and advection. The mixed layer depth is also an important factor determining the effect. The chlorophyll-induced SST warming appears in most regions during the local spring to autumn when the mixed layer is shallow, e.g., low latitudes without upwelling and the mid-latitudes. Chlorophyll-induced SST cooling appears in regions experiencing strong upwelling, e.g., the western Arabian Sea, west coast of North Africa, South Africa and South America, the eastern tropical Pacific Ocean and the Atlantic Ocean, and strong mixing (with deep mixed layer depth), e.g., the mid-latitudes in winter.

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.

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.