The compressibility of seawater from 0 to 95°C at 1atm

Measurements on the speed of sound (U) in seawater as a function of salinity at 1atm (P=0bar applied pressure) have been measured from 25 to 95°C. The new measurements have been combined with the earlier studies to determine the adiabatic compressibility (β_S=-(1/ρ)(∂ρ/∂P)_S) of seawater from 0 to 95°CβS=1/ρU2where ρ is the density and S is the entropy of seawater. The isothermal compressibility of seawater were determined fromβT=βSα2T/ρCpwhere the thermal expansively, α=-(1/ρ)(∂ρ/∂T)_P and heat capacity (Cp) were determine from earlier measurements. The values of the isothermal compressibility at 1atm (β_T⁰) have been used to estimate the effect of pressure on the secant bulk modulus of seawater (K^P at applied pressure P)KP=v0P/v0-vP=K0+A P+B P2where the specific volume v=1/ρ and K⁰=1/(β_T⁰). The values of A and B at high pressures have been determined from literature high pressure measurements. This allows one to make reasonable estimates of the density of seawater as a function of pressure to 100°C when seawater is used as a cooling agent and for desalination (Feistel, 2010).