Pierson, Tick, and Baer 



component has the behavior predicted by these theories in that the growth is at 

 first quite slow and linear and then growing to the full amplitude rather quickly 

 once a certain minimum is reached. The evaluation by Snyder and Cox, for ex- 

 ample, led to the conclusion that the Miles term was about eight times smaller 

 than is actually needed to explain the growth of the spectral component they 

 investigated. 



Inoue (18) in some recent work has attempted to use the functional forms 

 postulated in the theories of Miles and Phillips with constants picked in such a 

 way that the growth will match the growth which was observed in the data pro- 

 vided by the British shipborne wave recorder. The first effort employed a flat 

 growth independent of frequency for the Phillips term, and the functional form 

 of the Miles term increased by a factor of about eight to model the Miles term. 

 This effort indicated a growth of significant wave height versus fetch (and dura- 

 tion) very much like that obtained by Sverdrup and Munk many years ago. Cur- 

 rent investigation involves the study of a more realistic Phillips term in which 

 the spectral growth will be a function of both frequency and wind speed. The 

 spectral growth from a flat, calm ocean with a 40-knot wind according to Inoue 

 (18) is shown in Fig. 1. 



S( 

 m^sec 



120 

 100 

 80 

 60 

 40 

 20 



030 0.040 0.060 0.080 0.100 0.120 



frequency {sec"') 



0.140 



0.160 



Fig. 1 - Spectral growth from a flat calm ocean with a wind of 40 knots 

 19.5 meters above the sea surface 



502 



