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IAPWS R13-08
Release on the IAPWS Formulation 2008 for the Thermodynamic Properties of Seawater
September 2008

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This formulation is recommended for the calculation of thermodynamic properties of IAPSO standard seawater, including equilibria with liquid water, water vapor, or ice Ih, in combination with the IAPWS Releases for fluid water and for ice Ih.
The formulation is for the Gibbs energy as a function of salinity, temperature and pressure; appropriate combinations of derivatives can produce any thermodynamic property desired (density or specific volume, sound speed, heat capacity, enthalpy, entropy, chemical potential, etc.).
The formulation is valid in the entire region of ambient ocean water, and for thermal and colligative properties at atmospheric pressure up to 80 °C in temperature and up to 120 g/kg in absolute salinity on the 2008 Reference-Composition salinity scale.
The development of the formulation and comparisons to available data are described in detail in a scientific article.

Software Implementation
The IAPWS Subcommittee on Seawater, in cooperation with the SCOR/IAPSO Working Group 127, developed the "Thermodynamic Equation of Seawater 2010" (TEOS-10) which was endorsed as an international standard for oceanography by UNESCO-IOC in 2009 and by IUGG in 2011. The open-source code of TEOS-10 includes software implementations of this IAPWS formulation. Note that IAPWS is not responsible for the content of these external pages.

Revision History

This Release is the product of the Working Group "Thermophysical Properties of Water and Steam" (TPWS) and the Subcommittee on Seawater (SCSW) of the International Association for the Properties of Water and Steam (IAPWS).

This page updated July 10, 2020

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