Date post: | 05-Jan-2016 |
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Nominal SVP (Sound Velocity Profile)
4850ft/s 4900 ft/s 4950 ft/s 5000ft/s
Speed of Sound
300 600
3000
6000
9000
Surface Layer
Seasonal Thermocline
Main Thermocline
Deep Isothermal Layer
winter
“Layer”
Typical SVP
Gradients and Bending
c
z
c
c
z
z
Iso-speed
positive
negative
Surface Duct – Surface Shadow Zone
SVP
SVP
positive
negative
Surface Shadow Zone Implications
Originally called the “afternoon effect”
Convergence Zone
Depth Excess > 300 fathoms
CZ Effect on Transmission Loss (TL)
TL (dB)
Deep Shadow Zones
BD = 17(LD)1/2 if LD < 60m.BD = 17(LD)1/2 if LD < 60m.BD = LD + 60m if LD > 60m.BD = LD + 60m if LD > 60m.
Deep sound channelSound speed
dept
h
range
Mixed Layer Example
• 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
D = 40 mL = 100 mC1 = 1500 m/sg = 0.017 s-1
S
Mixed Layer
Summary
Positive gradient, g
z1
z2
x1 x2
c1
c2
1
2
R
1 1x x R sin sin
1 1z z R cos cos
1
1
cR
g cos
1
1
cos cos
c c
1
1
c c cg
z z z