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The density of seawater as a function of salinity (5 to 70 g kg
Rosenstiel School of Marine and Atmospheric Science, University of Miami, Miami, FL 33149, USA
Abstract. New seawater density measurements were made as a function of temperature (0 to 90°C) and salinity (5 to 70). The measurements (N=230) from 0 to 40°C and Practical Salinity from 0 to 40 were found to be in good agreement (σ=0.0036) with the equation of state of seawater (Millero and Poisson, 1981) made on samples with a known chlorinity (Cl). These results indicate that the Practical Salinities (S) are in agreement to within ±0.003 with the values calculated from the Chlorinity, SCl=1.80655 Cl. The measurements from 25 to 90°C were used to extend the equation of state to high temperatures and salinities. All the relative densities (ρ−ρ0, where ρ0 is the density for pure water) were fitted to equations of the form
(ρ−ρ0)/kg m−3 = ASA + BSA0.5 + CSA2
where A, B, and C are functions of temperature and SA (g kg−1) is the absolute salinity, SA=(35.16504/35)S. The fitted results from SA=0 to 50 and 0 to 40°C (N=247) gave standard errors of 0.0037 kg m−3. The fitted results from 25 to 90°C (N=271) gave standard errors of 0.0063 kg m−3 and all the results (N=501) from 0 to 90°C gave standard errors of 0.0062 kg m−3. The earlier density measurements used to determine the equation of state of seawater were combined to derive equations that are valid from 0 to 40°C and 0 to 90°C. The standard errors of these fits are, respectively, 0.0038 kg m−3 (N=713) and 0.0063 kg m−3 (N=962). These new measurements expand the equation of state of seawater to a wider range of temperature (0 to 90°C) and absolute salinity (0 to 70).
Discussion Paper (PDF, 874 KB) Supplement (20 KB) Interactive Discussion (Closed, 6 Comments) Final Revised Paper (OS)
Citation: Millero, F. J. and Huang, F.: The density of seawater as a function of salinity (5 to 70 g kg
