Sigma-t
# Sigma-t

Sigma-t is a quantity used in oceanography to measure the density of seawater 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.

