Del Grosso's equation

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An alternative equation to the UNESCO algorithm, which has a more restricted range of validity, but which is preferred by some authors, is the Del Grosso equation (1974)Wong and Zhu (1995) also reformulated this equation for the new 1990 International Temperature Scale and their version is:

Interactive Version

c(S,T,P) =   C000 + CT + CS + CP + deltaCSTP  
 
  CT(T) = CT1T + CT2T2 + CT3T3
  deltaCS(S) = CS1S + CS2S2
  deltaCP(P) = CP1P + CP2P2 + CP3P3
  deltaCSTP(S,T,P) =  CSTST + CTPTP + CTP2TP2 + CT3PT3P + CT2P2T2P2 + CTP3TP3 + CST2ST2 + CSTPSTP + CS2TPS2TP + CS2P2S2P2
 
  T = temperature in degrees Celsius
S = salinity in Practical Salinity Units
P = pressure in kg/cm2

Range of validity: temperature 0 to 30 C, salinity 30 to 40 parts per thousand, pressure 0 to 1000 kg/cm2, where 100 kPa=1.019716 kg/cm2(Wong and Zhu, 1995).

Please note that for consistency, within the interactive version, the pressure must be input in kPa.

Table of Coefficients
Coefficients Numerical values
C000 1402.392
CT1 0.5012285E1
CT2 -0.551184E-1
CT3 0.221649E-3
CS1 0.1329530E1
CS2 0.1288598E-3
CP1 0.1560592
CP2 0.2449993E-4
CP3 -0.8833959E-8
CST -0.1275936E-1
CTP 0.6353509E-2
CT2P2 0.2656174E-7
CTP2 -0.1593895E-5
CTP3 0.5222483E-9
CT3P -0.4383615E-6
CS2P2 -0.1616745E-8
CST2 0.9688441E-4
CS2TP 0.4857614E-5
CSTP -0.3406824E-3


(1)V.A. Del Grosso, New equation for the speed of sound in natural waters (with comparisons to other equations) (1974) J. Acoust. Soc. Am 56(4) pp 1084-1091

(2)G.S.K. Wong and S Zhu, Speed of sound in seawater as a function of salinity, temperature and pressure (1995) J. Acoust. Soc. Am. 97(3) pp 1732-1736