# SeawaterPolynomials.jl

This package provides approximations to the Boussinesq equation of state for seawater expressed as polynomial functions of conservative temperature, absolute salinity, and geopotential height.

Computationally efficient polynomial approximations to the Boussinesq seawater equation of state are crucial components of ocean modeling software.

## The Seawater Boussinesq approximation

In the seawater Boussinesq approximation, the density of seawater is expanded around a constant reference value, $ρᵣ$,

\[ρ = ρ_r + ρ'(Θ, Sᴬ, Z) ,\]

where the anomaly, $ρ'$, is a function of conservative temperature $Θ$, absolute salinity $Sᴬ$, and geopotential height $Z$. One choice for $ρ_r$ is the average density at the surface of the world ocean, $ρ_r = 1024.6 \, \text{kg} \, \text{m}^{-3}$, according to Roquet et al. (2015).

## The TEOS-10 standard

The Thermodynamic Equation of SeaWater (TEOS-10) is a Gibbs function formulation of seawater thermodynamics.

The error between the polynomials implemented in this package and the TEOS-10 is minimized for current 'climatological' ocean distributions of conservative temperature and absolute salinity. For more information, see

## Related packages

# References

Roquet et al., "Accurate polynomial expressions for the density and specific volume of seawater using the TEOS-10 standard",

*Ocean Modelling*(2015).Roquet et al., "Defining a Simplified Yet “Realistic” Equation of State for Seawater",

*Journal of Physical Oceanography*(2015).Young, W. R., "Dynamic Enthalpy, Conservative Temperature, and the Seawater Boussinesq Approximation",

*Journal of Physical Oceanography*(2010)