Observations and Measurements of Ocean Waves 



55 



U 



Cqtt?!/ 



3 1 



32 g* 



— v 



(III. 11) 



The total energy accumulated in the composite wave motion of a fully arisen 

 sea increases in proportion to the fifth power of the wind speed. The con- 

 stant C can be determined from observations (Neumann, 1953a), and 

 one obtains with C = 8-27 :■: 10" 4 sec -1 , q~1 and g = 981 cm/sec 2 and 

 v in cm/sec 



U = 3-125 x 10^ 9 r 5 [ergcm- 2 ] . (III. 12) 



The actual wave spectrum of a sea is obtained by harmonic analysis of 

 recordings of sea motion; this procedure is based on the conception that 



£, 



0-06 



OiO 



014 



018 



0-22 



0-26 



Fig. 33. Co-cumulative power spectra for ocean waves at wind velocities between 20 and 

 36 knots. The ordinate Ef are proportional to the total wave pattern and determine the 



height characteristics of the sea. 



the actual wave motion results from a linear superposition of harmonic 

 waves according to the principle of Fourier. The wave analysis is done by 



