In June of 2009 the Intergovernmental Oceanographic Commission (IOC), with the endorsement of the Scientific Committee on Oceanic Research (SCOR) and the International Association of the Physical Sciences of the Oceans (IAPSO) adopted the Thermodynamic Equation Of Seawater - 2010 (TEOS-10), as the official description of seawater and ice properties in marine science. All oceanographers are now urged to use the new TEOS-10 algorithms and variables to report their work. We anticipate that within two years (2012) oceanographers will have completely migrated to TEOS-10.
The TEOS-10 properties of seawater are all derived from a Gibbs function (by mathematical processes such as differentiation) and so are totally consistent with each other and furthermore are reversible (in contrast to the now obsolete EOS-80 approach where separate polynomials were provided for each thermodynamic variables and so they were not mutually consistent).
Two notable differences of TEOS-10 compared with EOS-80 are
(1) the adoption of Absolute Salinity to describe the salinity of seawater; Absolute Salinity takes into account the spatially varying composition of seawater, and
(2) the adoption of Conservative Temperature in place of potential temperature. Both of these temperatures are calculated quantities that result from an artificial thought experiment (namely, an adiabatic and isohaline change in pressure to the sea surface). Conservative Temperature has the advantage that it better represents the “heat content” of seawater, by two orders of magnitude and there seems no reason to continue the use of potential temperature in oceanography.
To enable oceanographers to take the steps towards fully implementing TEOS-10, the Gibbs SeaWater (GSW) Oceanographic Toolbox of TEOS-10 has been developed and is freely available from www.teos-10.org.
This GSW Oceanographic Toolbox will be of particular interest to the oceanic community because the input variables are expressed in standard oceanographic (as opposed to SI) units, and because the algorithms are computationally efficient. This toolbox contains the functions to compute Absolute Salinity (SA) and Conservative Temperature (CT) as well as a comprehensive collection ocean properties functions based on SA and CT, ie. density, dynamic height, geostrophic streamfunctions, conversion of depth to pressure, buoyancy (Brunt-Vaisala) frequency, enthalpy, entropy, sound speed.