The Hydrographic Society (Pike and Beiboer, 1993) has a good summary of the main algorithms for sound speed in the ocean. For further discussion on this topic, please refer to Dushaw et al (1993), Meinen and Watts (1997), Millero and Xu Li (1994), Speisberger and Metzger (1991a, 1991b) and Speisberger (1993). The choice of equation may depend on the accuracy and precision which is acceptable for the particular application in which it is being employed. It is important to recognise that the equations presented here are derived from fitting to experimental data from several different experiments and each has an associated uncertainty in its prediction of sound speed. Some researchers prefer Del Grosso’s equation, especially for calculations within its own domain of validity. UncertaintiesĪlthough the UNESCO algorithm is the International Standard algorithm, there is much debate in the scientific literature about the accuracy and range of applicability of this equation and of Del Grosso’s equation. A full range of corrections may be found in Leroy and Parthiot (1998).įor consistency the interactive version returns a pressure in kPa. These are defined as open oceans between the latitudes of 60°N and 40°S, and excluding closed ocean basins and seas. ![]() The correction h 0Z is the correction applicable to common oceans. Leroy and Parthiot (1998) give a table of corrections which are needed when the standard formula is applied to specific oceans and seas. In the above equation, P (=h(Z,Φ)) would apply to the oceanographers’ standard ocean, defined as an ideal medium with a temperature of 0 ☌ and salinity of 35 parts per thousand. This equation was created out of a need for an equation that was suitable for use in all ‘neptunian’ waters excluding the abnormal ‘hot spots’ of abnormally high temperature and salinity, in order to enable a person to accurately calculate the speed of sound in various scenarios using only a single equation. The most recent equation for the speed of sound in seawater is the NPL Equation as formulated by Leroy, Robinson and Goldsmith (2008). Please note that for consistency, within the interactive version, the pressure must be input in kPa Table of Coefficients Range of validity: temperature 0 to 30 ☌, salinity 30 to 40 parts per thousand, pressure 0 to 1000 kg/cm 2, where 100 kPa=1.019716 kg/cm 2. Wong and Zhu (1995) also reformulated this equation for the new 1990 International Temperature Scale and their version is: Table of CoefficientsĪn 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). ![]() Please note that for consistency, within the interactive version, the pressure must be input in kPa. Range of validity: temperature 0 to 40 ☌, salinity 0 to 40 parts per thousand, pressure 0 to 1000 bar (Wong and Zhu, 1995).
0 Comments
Leave a Reply. |