- 58 - 



n^(x,y,t) = 



— k cos 6 sin (k x + k y - at) 

 2 X y 



(in. /in.) (4.A1) 



and 



n (x,y,t) 



— k sin 6 sin (k x - k y - at) 

 2 x y 



(in. /in.) (A.A2) 



while the curvature, or acceleration, terms are as: 



n^^(x,y,t) = 



— k cos cos(k x + k y - at) 

 2 X y 



(in.-1) (4. A3) 



and 



n {x,y,t) 



yy 



- — k sin cos (k x - k y - at) 

 2 X y 



(in.-i) (4.44) 



Twice the sum of the squares of the modified Fourier 

 coefficients represents the power spectrum of the displacement, slope 

 components, and curvature components. The significant wave height is 

 determined from four times the square root of the sum of the absolute 

 channel's power spectrum: 



H. ._ = 4/S 



1/3 tin 



(4.45) 



