TEOS-10
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TEOS-10 (Thermodynamic Equation of Seawater - 2010) is the international standard for the use and calculation of the thermodynamic properties of seawater, humid air and ice. It superseeds the former standard EOS-80 (Equation of State of Seawater 1980) [1].
History
TEOS-10 was developed by the SCOR(Scientific Committee on Oceanic Research)/IAPSO(International Association for the Physical Sciences of the Oceans) Working Group 127 [2] and has been approved as the official description of the thermodynamic properties of seawater, humid air and ice in 2009 by the Intergovernmental Oceanographic Commission (IOC)[3] and in 2011 by the International Union of Geodesy and Geophysics (IUGG)[4].
Physical basis
TEOS-10 is based on thermodynamic potentials. While closed thermodynamic systems are often defined by the Helmholtz energy F(m,T,V), TEOS-10 uses the specific Gibbs potential g(T,P)=G/m to calculate thermodynamic properties, because the pressure is a more measurable property than volume in a geophysical context. [5] The thermodynamic potential functions are determined by a set of adjustable parameters which are tuned to fit experimental data. Since absolute energy and entropy cannot be directly measured a reference state for liquid water, seawater and dry air are defined as following:
- liquid water: internal energy and entropy at solid-liquid-gas triple point are zero
- seawater: entropy and enthalpy are zero at SP(Practical Salinity)=35.16504 g/kg, T(Temperature)=273.15 K, p(pressure)=101325 Pa
- dry air: entropy and enthalpy are zero at T(Temperature)=273.15 K, p(pressure)=101325 Pa [5]
Included thermodynamic properties
The thermodynamic properties covered by TEOS-10 include, but are not limited to, basic properties like the ITS-90 temperature, sea pressure, the Gibbs function of seawater and sound speed.
Additionally, TEOS-10 covers derived properties, for example the potential and conservative temperature, the buoyancy frequency, the planetary vorticity and the Montgomery and Cunningham geostrophic streamfunctions. A complete list of featured properties can be found in the TEOS-10 Manual.
The handling of salinity was one of the novelties in TEOS-10. It defines the relationship between reference salinity and practical salinity or reference salinity and chlorinity and accounts for the different chemical compositions (Media: Absolute Salinity Anomaly) by adding a geographically dependent 𝛿SA.
Software packages
TEOS-10 includes the Gibbs Seawater (GSW) Oceanographic Toolbox which is available for MATLAB, Fortran, Python, C, C++, R, Julia and PHP. While TEOS-10 is generally SI-units, the GSW package uses in- and output data in widely used oceanographic units (i.e. g/kg for Absolute Salinity SA).[6]
Additionally to the GSW Oceanographic Toolbox, the Seawater-Ice-Air (SIA) Library, available for Fortran and Visual Basic, covers the thermodynamic properties of seawater, ice and (moist) air. Opposite to the GSW Toolbox, here SI-units are used.[7]
External links
The Gibbs-Seawater (GSW) Oceanographic Toolbox functions
References
- ^ "PreTEOS-10 software". Retrieved 28 May 2021.
- ^ Pawlowicz, R.; et al. (2012). "An historical perspective on the development of the Thermodynamic Equation of Seawater--2010". Ocean Science. 8 (2): 161–174. Bibcode:2012OcSci...8..161P. doi:10.5194/os-8-161-2012. Retrieved 12 May 2021.
{{cite journal}}: CS1 maint: unflagged free DOI (link) - ^ IOC. Reports of governing and major subsidiary bodies (16–25 June 2009). "2.5" (PDF). Twenty-fifth Session of the Assembly. Paris: UNESCO. p. 4.
- ^ XXV General Assembly of the International Union of Geodesy and Geophysics (27 June – 8 July 2011). Minutes of the Council Meeting (PDF). Melbourne. pp. 54, Resolution:4.
- ^ a b Feistel, Rainer (2018). "Thermodynamic properties of seawater, ice and humid air: TEOS-10, before and beyond" (PDF). Ocean Science. 14 (3): 471–502. Bibcode:2018OcSci..14..471F. doi:10.5194/os-14-471-2018. Retrieved 12 May 2021.
{{cite journal}}: CS1 maint: unflagged free DOI (link) - ^ McDougall, T.J.; Barker, P.M. (2011). Getting started with TEOS-10 and the Gibbs Seawater (GSW) Oceanographic Toolbox (PDF). SCOR/IAPSO WG127. p. 28. ISBN 978-0-646-55621-5. Retrieved 16 May 2021.
- ^ IOC, SCOR and IAPSO (2010). The international thermodynamic equation of seawater – 2010: Calculation and use of thermodynamic properties (PDF). Intergovernmental Oceanographic Commission, Manuals and Guides No. 56. UNESCO (English). p. 171. Retrieved 16 May 2021.