Mutually consistent thermodynamic potentials for fluid water, ice and seawater: a new standard for oceanography

[摘要] A new seawater standard for oceanographic and engineering applications hasbeen developed that consists of three independent thermodynamic potentialfunctions, derived from extensive distinct sets of very accurateexperimental data. The results have been formulated as Releases of theInternational Association for the Properties of Water and Steam, IAPWS(1996, 2006, 2008) and are expected to be adopted internationally by otherorganizations in subsequent years. In order to successfully performcomputations such as phase equilibria from combinations of these potentialfunctions, mutual compatibility and consistency of these independentmathematical functions must be ensured. In this article, a brief review oftheir separate development and ranges of validity is given. We analysebackground details on the conditions specified at their reference states,the triple point and the standard ocean state, to ensure the mutualconsistency of the different formulations, and the necessity and possibilityof numerically evaluating metastable states of liquid water. Computed fromthis formulation in quadruple precision (128-bit floating point numbers),tables of numerical reference values are provided as anchor points for theconsistent incorporation of additional potential functions in the future,and as unambiguous benchmarks to be used in the determination of numericaluncertainty estimates of double-precision implementations on differentplatforms that may be customized for special purposes.

[学科分类] 海洋学与技术