Calculation and measurements

Many empirical relationships have been developed over the years for calculating sound speed using values of water temperature, salinity and pressure (or depth). Frequently used formulas include those of Wilson (1960), Leroy (1969), Frye and Pugh (1971), Del Grosso (1974), Medwin (1975), Chen and Millero (1977), Lovett (1978), Coppens (1981) and Mackenzie (1981). As summarized in Table 2.1, each formula has its own ranges of temperature, salinity and pressure (or depth). Collectively, these ranges are referred to as "domains of applicability." Calculations outside of the specified domains may lead to errors. The individual equations are not reported in Table 2.1. However, the number of terms comprising each equation is indicated in the far-right column. The simplest equation (Medwin, 1975) contains six terms while the most complicated equation (Wilson, 1960) contains 23 terms.

Table 2.1 Summary of sound-speed algorithm parameter ranges


Temperature range (°C)

Salinity range (ppt)

Pressure or depth rangea

Standard error (mr1)

Number of terms

Wilson (1960)

0 0

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