1. Nominal SVP (Sound Velocity Profile)
4850ft/s ft/s ft/s ft/s
Speed of Sound
300
600
3000
6000
9000
Surface Layer
Seasonal Thermocline
Main Thermocline
Deep Isothermal Layer
winter
“Layer”

2. Typical SVP

3. Gradients and Bending
c  z  c
Iso-speed
positive
negative

4. Surface Duct – Surface Shadow Zone
SVP
positive
SVP
negative

5. Surface Shadow Zone Implications
Originally called the “afternoon effect”

6. Convergence Zone
Depth Excess > 300 fathoms

7. CZ Effect on Transmission Loss (TL)
TL (dB)

8. Deep Shadow Zones BD = 17(LD)1/2 if LD < 60m.
BD = LD + 60m if LD > 60m.

9. Deep sound channel
Sound speed
range
depth

10. Mixed Layer Example Find sound speed at S and at bottom of layer
D = 40 m
L = 100 m
C1 = 1500 m/s
g = s-1 S
Find sound speed at S and at bottom of layer
Angle of the rays at the source
Angle of the rays at the surface
Radius of curvature of the ray
Skip distance , X

11. Mixed Layer

12. Summary
Positive gradient, g z1 z2 x1 x2 c1 c2 q1 q2 R