(p,ρ,T) properties of seawater: Extensions to high salinities

Measurements of (p,ρ,T) properties of seawater with absolute salinity SA=(31.684, 33.507, 37.372, 37.969, 40.164, 41.825, 44.811, 46.119, 48.600, 50.232, 52.449 and 55.529) g kg−1, temperature T=273.15–468.15 K and pressures, p, up to 140 MPa are reported with the reproducibility of the density measurements observed to be in the average percent deviation range Δρ/ρ=±0.01–0.03%. The measurements are made with a new set up vibration-tube densimeter which is calibrated using double-distilled water (Wagner and Pruß, 2002), methanol [(de Reuck and Craven, 1993), (Osada et al., 1999) and (Yokoyama and Uematsu, 2003)] and aqueous NaCl solutions [(Archer, 1992) and (Hilbert, 1979)]. Based on these measurements, an empirical expression for the density of seawater at high salinities has been developed as a function of salinity, pressure and temperature. The results can be used to extend the present equation of state of seawater to higher temperatures for pressure up to 140 MPa.