11-14 



The general behavior derived above has been substantiated pretty well 

 by experimental evidence. As an example, we show in Figure II-6 some measure- 

 ments of the coefficient of variation, which exhibit the dependence as the square 

 root of the range to be expected outside the focusing range. There is quite a wide 

 scatter about the curve, and this is typical for any ocean measurements of scat- 

 tering phenomena. 



In conclusion, we show in Figure II- 7 some measurements of the coef- 

 ficient of variation made by the Ordnance Research Laboratory both for a signal 

 traveling along the direct path and for the same signal traveling along the surface- 

 reflected path. The coefficient of variation along the direct path increases effec- 

 tively as the square root of the range. At short ranges, the surface- reflected path 

 has a much greater coefficient of variation (i.e. , a much greater percentage of 

 scattered power). This is due to the effect, which we discussed earlier, of rela- 

 tively high diffuse scattering from a corrugated surface near normal incidence. 

 As the range gets longer and the angle of incidence becomes smaller, the higher 

 order non- specular terms of reflection become less important. Finally, for very 

 small grazing angles, the power scattered by the inhomogeneities of the surface 

 become negligible, and the coefficient of variation along the surface -reflected 

 path approaches that along the direct path. 



artbur 21.1littlc.3nt. 



S-7001-0307 



