Mutually consistent thermodynamic potentials for fluid water, ice and seawater: a new standard for oceanography
1Leibniz Institute for Baltic Sea Research, 18119 Warnemünde, Germany
2Bedford Institute of Oceanography, Dartmouth, NS, Canada
34-12-11-628, Nishiogu, Arakawa-ku, Tokyo 116-0011, Japan
4National Institute of Standards and Technology, Boulder, CO 80305, USA
5Institute of Thermomechanics of the ASCR, v.v.i., Prague, Czech Republic
6Centre for Australian Weather and Climate Research: A partnership between CSIRO and the Bureau of Meteorology, Hobart, TAS, Australia
7Ruhr-Universität Bochum, 44780 Bochum, Germany
Abstract. A new seawater standard for oceanographic and engineering applications has been developed that consists of three independent thermodynamic potential functions, derived from extensive distinct sets of very accurate experimental data. The results have been formulated as Releases of the International Association for the Properties of Water and Steam, IAPWS (1996, 2006, 2008) and are expected to be adopted internationally by other organizations in subsequent years. In order to successfully perform computations such as phase equilibria from combinations of these potential functions, mutual compatibility and consistency of these independent mathematical functions must be ensured. In this article, a brief review of their separate development and ranges of validity is given. We analyse background details on the conditions specified at their reference states, the triple point and the standard ocean state, to ensure the mutual consistency of the different formulations, and the necessity and possibility of numerically evaluating metastable states of liquid water. Computed from this formulation in quadruple precision (128-bit floating point numbers), tables of numerical reference values are provided as anchor points for the consistent incorporation of additional potential functions in the future, and as unambiguous benchmarks to be used in the determination of numerical uncertainty estimates of double-precision implementations on different platforms that may be customized for special purposes.
Feistel, R., Wright, D. G., Miyagawa, K., Harvey, A. H., Hruby, J., Jackett, D. R., McDougall, T. J., and Wagner, W.: Mutually consistent thermodynamic potentials for fluid water, ice and seawater: a new standard for oceanography, Ocean Sci., 4, 275-291, doi:10.5194/os-4-275-2008, 2008.