Del Grosso

Del Grosso's equation

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 + C_T + C_S + C_P + C_STP

	C_T(T) = C_T1T + C_T2T² + C_T3T³
	C_S(S) = C_S1S + C_S2S²
	C_P(P) = C_P1P + C_P2P² + C_P3P³
	C_STP(S,T,P) = C_STST + C_TPTP + C_TP2TP² + C_T3PT³P + C_T2P2T²P² + C_TP3TP³ + C_ST2ST² + C_STPSTP + C_S2TPS²TP + C_S2P2S²P²

	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.

Coefficients	Numerical values
Table of Coefficients
C₀₀₀	1402.392
C_T1	0.5012285E1
C_T2	-0.551184E-1
C_T3	0.221649E-3
C_S1	0.1329530E1
C_S2	0.1288598E-3
C_P1	0.1560592
C_P2	0.2449993E-4
C_P3	-0.8833959E-8
C_ST	-0.1275936E-1
C_TP	0.6353509E-2
C_T2P2	0.2656174E-7
C_TP2	-0.1593895E-5
C_TP3	0.5222483E-9
C_T3P	-0.4383615E-6
C_S2P2	-0.1616745E-8
C_ST2	0.9688441E-4
C_S2TP	0.4857614E-5
C_STP	-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