Sigma-t is a quantity used in
oceanography to measure the
density
Density (volumetric mass density or specific mass) is the substance's mass per unit of volume. The symbol most often used for density is ''ρ'' (the lower case Greek letter rho), although the Latin letter ''D'' can also be used. Mathematical ...
of
seawater
Seawater, or salt water, is water from a sea or ocean. On average, seawater in the world's oceans has a salinity of about 3.5% (35 g/L, 35 ppt, 600 mM). This means that every kilogram (roughly one liter by volume) of seawater has appr ...
at a given temperature.
σ
T is defined as ρ(S,T)-1000 kg m
−3, where ρ(S,T) is the density of a sample of seawater at temperature T and salinity S, measured in
kg m−3, at standard atmospheric pressure. For example, a water sample with a density of 1.027 g/cm
3 has a σ
T value of 27.
References
{{reflist, 28em
See also
*
Density of saltwater and ice
Units of density