Compressibility of distilled water and seawater

Abstract

The compressions of distilled water and of seawater of approximately 31, 35, and 39% salinity were measured at 10°C for pressures up to 1000 bars. The data were summarized by a ‘best’ least-square fit polynomial in pressure and salinity. The summary formula was combined withBryden's (Deep-Sea Research,20, 401–408, 1973) similar type fit to our earlier thermal expansion data (Bradshaw andSchleicher, Deep-Sea Research,17, 691–706, 1970) andFofonoff andBryden's (Journal of Marine Research, in press) recent empirical formula for sigma-0 of seawater to give an expression for the specific volume of seawater as a function of temperature, pressure and salinity in the salinity range 31 to 39%. At 35% specific volumes from this expression in the oceanographic range of temperature and pressure agree within 15 × 10⁻⁶cm³g⁻¹ with those computed using sound velocities (Wang andMillero, Journal of Geophysical and Research,78, 7122–7128, 1973). Our mean compressibilities for distilled water at 10°C also agree with those from sound velocities (to within 0·05%) but disagree with those ofKell andWhalley (Philosophical Transactions of the Royal Society of London, A,258, 565–614, 1965) by about 0·3%.