The International thermodynamic equation of ... - unesdoc - Unesco

ΣΑ = Δρ/0Σ– A Summary for Policy Makers2010ΣΑThe InternationalThermodynamicEquation of SeawaterAdvantages of TEOS-108© CSIROThe more prominent advantages of TEOS-10compared with EOS-80 are: lationof internal energy, entropy, enthalpy,potential enthalpy and the chemical potentialsof seawater as well as the freezingtemperature, and the latent heats of freezingand of evaporation. These quantities werenot available from the International Equationof State 1980 but are essential for the accurateaccounting of “heat” in the ocean andfor the consistent and accurate treatment ofair-sea and ice-sea heat fluxes. For example,a new temperature variable, ConservativeTemperature, can be defined as being proportionalto potential enthalpy and is a valuablemeasure of the “heat” content per unit massof seawater for use in physical oceanographyand in climate studies, as it is approximatelytwo orders of magnitude more conservativethan both potential temperature and entropy. varying composition of seawater can systematicallybe taken into account through theuse of Absolute Salinity. In the open ocean,this has a non-trivial effect on the horizontaldensity gradient computed from the equationof state, and thereby on the ocean velocitiesand heat transports calculated via the“thermal wind” relation. the new approach are totally consistent witheach other, and can now account for propertiessuch as speed of sound and the compressibilityof water with depth. measured in SI units. Moreover the treatmentof freshwater fluxes in ocean models will beconsistent with the use of Absolute Salinity,but is only approximately so for PracticalSalinity. seawater supports marine physicochemicalstudies such as the solubility of sea saltconstituents, alkalinity, pH, and ocean acidificationfrom risingspheric CO 2 .concentrations of atmo-