Transcript Nominal SVP (Sound Velocity Profile)

Nominal SVP (Sound Velocity Profile)
Speed of Sound
4850ft/s
300
600
3000
6000
9000
4900 ft/s
winter
4950 ft/s
5000ft/s
Surface Layer
Seasonal Thermocline
Main
Thermocline
“Layer”
Deep
Isothermal
Layer
Typical SVP
Gradients and Bending
c 
z
Iso-speed

c 
z
positive

c
negative
z

Surface Duct – Surface Shadow Zone
SVP
positive
SVP
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
BD = LD + 60m
if LD < 60m.
if LD > 60m.
Deep sound channel
depth
Sound speed
range
Mixed Layer Example
S
•
•
•
•
•
D = 40 m
L = 100 m
C1 = 1500 m/s
g = 0.017 s-1
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
Mixed Layer
Summary
cos q1 cos q

c1
c
x2
x1
x  x1  R sin q  sin q1 
R
z1
z2
c1
c2
q1
q2
Positive gradient, g
z  z1  R  cos q  cos q1 
c1
R
g cos q1
c c  c1
g

z z  z1