•Che above description of the various vertical layers is a convenient 

 allzation and is not expected to be valid at all times in waters of all 

 Dths. Fo^ instance, the classical turbulent Ekman layer has a thickness on 

 the order of u*/f and is based on a steady-state force balance between the 

 wind stress and the Coriolis force in a neutrally stratified water column. In 

 reality, however, wind mixing seldom reaches the neutral Ekman layer depth due 

 to the presence of buoyancy and/or other dynamic processes (e.g., wind 

 forcing) containing time scales much smaller than the rotational time scale. 

 Strong convective mixing may also destroy the distinct Ekman spiral. Across 

 the air-sea interface, mutual interactions of atmosphere and ocean take place 

 within the ocean mixed layer and the atmospheric marine boundary layer. On 

 windy days, the air-sea interface is quite rough due to strong wave actions 

 and the ocean mixed layer is strongly influenced by the wave-turbulence 

 interactions. Turbulence generated by wave breaking plays a dominant role in 

 the mixed layer dynamics (as well as in the surf zone dynamics), but our 

 understanding on this subject is still rather primitive. Another factor 

 having strong influence on the mixed layer dynamics is the density 

 stratification. A stable stratification decreases the turbulent mixing while 

 an unstable stratification increases turbulent mixing. Strong convective 

 events in calm weather may lead to organized features similar to the rolls of 

 vortices in the atmosphere (Lewellen, Teske, and Sheng, 1980). In deep waters 

 below the surface mixed layer, patches of turbulence can be generated due to 

 the presence of internal waves. (Garrett and Munk, 1972 and 1975). 



In shallow coastal waters, the surface and bottom Ekman layers may merge 

 and are comparable to the water depth. Dynamics of the relatively thin 

 sublayers (~1 cm) and constant flux layers (~1 m) play rather important roles 

 in affecting the transport of such materials as heat, sediment, nutrient, 

 oxygen, and oil slick, which are introduced into the water bodies at the 

 surface or bottom boundaries. Oscillatory flow or roughness features may 

 introduce additional thin logarithmic layers adjacent to the boundary. Along 

 the bottom of shallow waters such as tidal marshes, vegetation canopy may also 

 exist. 



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