25
0688-SOM-00001, Rev: 02
© Tritech International Ltd.
Appendix C
Free Running mode can be customised to use the following formulae to calculate sound velocity based on
Bathymetric Data.
C.1. Chen & Millero Equation
Velocity of Sound (VoS) Algorithms Chen and Millero
Source: NPL Technical Guides – Speed of Sound in Sea-water
Validity: T = 0 to 40oC, S = 0 to 40psu, P = 0 to 100 bar (Wong and Zhu, 1995)
Table of Coefficients
Table of Coefficients
Coefficients
Numerical values
Coefficients
Numerical values
C
00
1402.388
A
02
7.166E-5
C
01
5.03830
A
03
2.008E-6
C
02
-5.81090E-2
A
04
-3.21E-8
C
03
3.3432E-4
A
10
9.4742E-5
C
04
-1.47797E-6
A
11
-1.2583E-5
C
05
3.1419E-9
A
12
-6.4928E-8
C
10
0.153563
A
13
1.0515E-8
C
11
6.8999E-4
A
14
-2.0142E-10
C
12
-8.1829E-6
A
20
-3.9064E-7
C
13
1.3632E-7
A
21
9.1061E-9
C
14
-6.1260E-10
A
22
-1.6009E-10
C
20
3.1260E-5
A
23
7.994E-12
C
21
-1.7111E-6
A
30
1.100E-10
C
22
2.5986E-8
A
31
6.651E-12
C
23
-2.5353E-10
A
32
-3.391E-13
C
24
1.0415E-12
B
00
-1.922E-2
C
30
-9.7729E-9
B
01
-4.42E-5
C
31
3.8513E-10
B
10
7.3637E-5
C
32
-2.3654E-12
B
11
1.7950E-7
A
00
1.389
D
00
1.727E-3
A
01
-1.262E-2
D
10
-7.9836E-6
(S,T,P) = Cw(T,P) + A(T,P)S + B(T,P)S
3/2
+ D(T,P)S
2
Cw(T,P) = (C
00
+ C
01
T + C
02
T
2
+ C
03
T
3
+ C
04
T
4
+ C
05
T
5
) +
(C
10
+ C
11
T + C
12
T
2
+ C
13
T
3
+ C
14
T
4
)P +
(C
20
+C
21
T +C
22
T
2
+ C
23
T
3
+ C
24
T
4
)P
2
+
(C
30
+ C
31
T + C
32
T
2
)P
3
A(T,P) = (A
00
+ A
01
T + A
02
T
2
+ A
03
T
3
+ A
04
T
4
) +
(A
10
+ A
11
T + A
12
T
2
+ A
13
T
3
+ A
14
T
4
)P +
(A
20
+ A
21
T + A
22
T
2
+ A
23
T
3
)P
2
+
(A
30
+ A
31
T + A
32
T
2
)P
3
B(T,P) = B
00
+ B
01
T + (B
10
+ B
11
T)P
D(T,P) = D
00
+ D
10
P
T = temperature in degrees Celsius
S = salinity in Practical Salinity Units (parts per thousand)
P = pressure in bar