The procedure adopted to estimate the turbulent structure is 

 first to determine in a general way the mean motion field associated 

 with the oceano This is done so that the extent of turbulence-producing 

 shear flows can be appreciated and so that an upper limit can be set on 

 the velocity fluctuations. 



The mean motion would be damped out unless it were maintained by 

 external forces. Because an equilibrium, of sorts existSj the dissipation 

 rate associated with the motion of the water must equal the rate at which 

 energy is supplied to the water in mechanical form from the exterior so 

 as to cause it to move. Although this energy eventually appears as heat, 

 it first contributes to the kinetic energy of large scale motions and is 

 transferred to a viscous loss mechanism by means of intermediate turbulent 

 motions. Consequently this dissipation rate is an important index of the 

 intensity of the turbulence and calculations are made to establish an 

 upper limit for this quantity. 



Finally, expected turbulent velocities and dissipation rates are 

 incorporated into models which consider shear flow, stability criteria, etc., 

 so as to try to determine eddy sizes and time scales which are, hopefully, 

 of an order of magnitude of those that actually occur in the ocean. 



For simplicity, all data will refer to the North Atlantic between 

 10°N and 60°N. 



Energy of the Ocean 

 If the velocity distribution in the mean flow throughout the ocean 

 were known, the problem of estimating the degree of turbulence would be 



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