VELOCITY (m/sec) 

 1496 1500 1504 



GRADIENT (1/sec) 

 -0.10 +0.10 



40 

 80 



120+ 



160 



200 



X 

 I— 

 a. 



LLI 



Q 



40 



80 

 120 

 160 

 200 



40 

 80 



120 

 160 

 200^ 



I I 



Piecewise Lineor 



Piecewfse Quadratic 



Cubic Spline 



Figure 1. Comparison of Sound Speed Representations and Gradients 



98 



