An Equation of State for Use in Ocean Models: Eckart’s Formula Revisited

Abstract

Approximate formulas for in situ density as a function of potential temperature, salinity, and pressure are determined for use in numerical models. The approach taken is similar to that of Mellor, but use of the Tumlirz equation of state results in formulas that are somewhat simpler and more computationally efficient. Comparison is made with results obtained from the full United Nations Educational, Scientific and Cultural Organization equation of state and with the results obtained from the sound speed equation of Del Grosso. The corresponding formulas relating in situ density to the in situ temperature are also given.