SEAWAY 



37 



o.:o 



0.10 



■COS 



CgVo^v')' 





" \^ 



,xx^x 



Observa+ions 

 Long Branch Wave Records 

 f May3, 1948 

 •i_Ma5 5, 1948 



] Octobers, 1948 

 ^ "[ocVoben, 19 48 



0.5 O.G 



Fig. 36 Ratio of wave heights of square of apparent wave p^riads, H'V- as observed 

 with different ratios of apparent wave period to wind speed v, in generating area 



(from Neumann, 1953) 



c;,H+;H)f ='H 



Fig. 37 Apparent wave periods and heights in a wave record 

 (from Neumann, 1953) 





7/2 



C ^ exp 



47r" 



(cm- sec~') 



27rt 



(75) 



With the suljstitution of the above value, equation (70) 

 becomes, 



dUr = C ~p^-„T' e.xp 



6s IT' 





(IT (76) 



where the constant C(sec^') has yet to be determined. 

 This is the first basic expression for the spectrum, giving 

 the wave-energy distribution as a function of the wave 

 period. The second form of the spectrum, the distribu- 

 tion of the wave energy as a function of the circular frc- 

 quency w = 2w/T is obtained by substituting into equa- 

 tion (76). 



f/o) = 



/TIO 



clT and 



<L 



Wr (IT 



Wave spectro -for tully 

 arisen sea a+ a wind 

 speed of 20, 30 and 40 

 Kno + s, respectively. 



Fig. 38 (from Neumann, 1953) 



thus obtaining the second basic expression 



dU 



-Cpcfr' 



o) ' exp 



■2g"- 



0.25 



(77) 



The relative energy distribution (wa\e spectrum) 



