-1000 



■& 



^ 



SloP^ 



.b— b tL. 



B^b— b- 



T — I — I — r- 



20 40 



~1 1 1 1 1 1 T" 



60 80 100 120 



AZIMUTH (degrees) 



■'§ 



Figure E-4 Artificially generated surface composed of orthogonal 

 trends with spectral parameters b= -1.5, a= 1.0 in the N-S 

 direction, and b= -1.0, a= 2.0 in the E-W direction. Azi- 

 muthally dependent spectral parameters are plotted below. 



211 



