CA^) = Y^CPnj) + s'TT n e"^Pm (1 - ^^)^ - s*7r n e"^^*(l - p*)^ (30) 



In the stage of fully developed complex wave motion C^(p) is 

 given by the expression (25). 



3) Energy dissipation due to tiirbulent wave motion 



Energy may be dissipated by viscosity (Du. ) or by turbulent 

 motion in the wave(D,,), The viscosity of the water is so slight 

 that this effect can be neglected when dealing with the growth of 

 real ocean "waves. Only the process of generation of primary wave- 

 lets, which are not breaking, is apparently influenced by viscosity 

 [14]. But the "sea" evidently is a turbulent wave motion, and when 

 considering its growth imder the action of wind the effect of turbul- 

 ence has to be taken into account by introduction of an "eddy vis- 

 cosity" or "virtual friction." 



The dissipation of wave energy due to a viscosity coefficient 

 lA, is given (H. Lamb [21]) by 



D^ = 2^[^) 6- V . (31) 



V/hen dealing with turbulent ocean waves which are characterized by 



a phase velocity ff" , or at a given wind velocity v by the ratio 



(T /v = p, and the steepness 2aA = 6, we may write in analogy to (31) 



D^ = 2M(p)Tr2ga^ , (32) 



where the ordinary viscosity coefficient ^ is replaced by a turb- 

 ulence coefficient or coefficient of eddy viscosity M[cm~ g sec ]. 

 This coefficient M naturally is not to be regarded as a physical 

 constant characteristic of the fluid like /^ (at a given salinity 

 and temperature of sea water), but it will depend upon the state of 

 the "sea" and on the wind velocity. Therefore M is written in (32) 



67 



