Recent determinations of deep ocean vertical eddy diffusion 

 coefficients, A , were made by Koczy (1956) and were based on measure- 

 ments of the concentration of radium. Values of about 10 gm cm sec 

 obtained near the bottom fell to values below 1 gm cm sec at a 

 height of 3 km. The viscosity of non-turbulent water is about 

 .01 gm cm" sec" . Therefore, the presence of turbulent motion in deep 

 ocean seems certain. 



These measurements allow an estimate of the energy lost by the 

 velocity gradient previously calculated to be necessary to maintain turbu- 

 lence. This energy is of the order of (Proudman, 1953) 



A i^)^ = 10x( 1.4x10"^)^ 

 V dz 



-5 -3 

 or 2x10 ergs cm . Again, the agreement obtained with the same value 



established for the maximum rate of energy supplied from outside the ocean 

 to maintain the turbulence is fortuitous. Nevertheless, the high gradient 

 is not inconsistent with the maximum rate of energy dissipation even though 

 it is inconsistent with the expected wind-induced or tidal gradients. If 

 the turbulence is not induced by a mean horizontal shear flow, two other 

 mechanisms come to mindi 1) large and small scale horizontal motions inter- 

 act to produce vertical fluctuations, and 2) internal waves in the strat- 

 ified medium interact with the horizontal eddies to produce an effective 

 vertical turbulent component of motion (Townsend, 1958). 



In shear flows, the eddy viscosity is equal to (Townsend, 1956) 



'dz' 



-15- 



