A(v,f) 



Pierson, Tick, and Baer 



A%^-" (27Tf)"" d 



(0.52)2 + - sin 



(0.33)2 \T /v \ 2 



+ - cos 6/ - 1 



v/c 



(10) 



where v is in meters/second, k is in meters ^, and c = g/27Tf . The growth of 

 the wave spectrum for a 40-knot wind with Eq. (10) replacing Eq. (8) is shown in 

 Fig. 6. 



0.030 0.040 



U,g J = 40 knots 

 Duration In hours 



0.060 



0.080 0.100 0.120 



frequency (sec') 



0.140 



0.160 



Fig. 6 - The growth of a spectrum for a 40-knot wind with Eq. (10) 

 replacing Eq. (8) in Eq. (7) 



There are several possibilities for further modification of Eq. (9). The low 

 frequencies do not seem to grow fast enough, so that a change in the two con- 

 stants is still possible. Also, from the analysis of the stability and roughness 

 length, it may be possible to represent the wind profile at each grid point by an 

 equation of the form 



V = V [z, T^-T,, S(«, 0)], 



and for the condition v = c = g/27Tf . , the height z^ . can be found: 



Zfi = Z [g/27Tf., T3-T,. S(2T7f.)] . 



(11) 



(12) 



510 



