# gsw_sigma2_CT_exact

    potential density anomaly with reference pressure
    of 2000 dbar, this being this particular potential
    density minus 1000 kg/m^3

## Contents

- USAGE:
- DESCRIPTION:
- INPUT:
- OUTPUT:
- EXAMPLE:
- AUTHOR:
- VERSION NUMBER:
- REFERENCES:

## USAGE:

    sigma2_CT_exact = gsw_sigma2_CT_exact(SA,CT)

## DESCRIPTION:

    Calculates potential density anomaly with reference pressure of 2000
    dbar, this being this particular potential density minus 1000 kg/m^3.
    This function has inputs of Absolute Salinity and Conservative
    Temperature.

    Note that this function uses the full Gibbs function.  There is an
    alternative to calling this function, namely gsw_sigma2(SA,CT), which
    uses the computationally efficient 75-term expression for specific
    volume in terms of SA, CT and p (Roquet et al., 2015).

    Click for a more detailed description of potential
    density anomaly with p_ref of 2000 dbar (sigma_2).

## INPUT:

    SA  =  Absolute Salinity                                        [ g/kg ]
    CT  =  Conservative Temperature                                [ deg C ]

    SA & CT need to have the same dimensions.

## OUTPUT:

    sigma2_CT_exact =  potential density anomaly with             [ kg/m^3 ]
                       respect to a reference pressure of 2000 dbar,
                       that is, this potential density - 1000 kg/m^3.

## EXAMPLE:

    SA = [34.7118; 34.8915; 35.0256; 34.8472; 34.7366; 34.7324;]
    CT = [28.8099; 28.4392; 22.7862; 10.2262;  6.8272;  4.3236;]

    sigma2_CT_exact = gsw_sigma2_CT_exact(SA,CT)

    sigma2_CT_exact =

      30.023190232854176
      30.283832597402807
      32.265717400800895
      35.474625433103029
      36.067249427311708
      36.492547357788226

## AUTHOR:

    Trevor McDougall & Paul Barker     [ help@teos-10.org ]

## VERSION NUMBER:

    3.05 (16th February, 2015)

## REFERENCES:

    IOC, SCOR and IAPSO, 2010: The international thermodynamic equation of
     seawater - 2010: Calculation and use of thermodynamic properties.
     Intergovernmental Oceanographic Commission, Manuals and Guides No. 56,
     UNESCO (English), 196 pp.  Available from the TEOS-10 web site.
      See Eqn. (A.30.1) of this TEOS-10 Manual.

    Roquet, F., G. Madec, T.J. McDougall, P.M. Barker, 2015: Accurate
     polynomial expressions for the density and specifc volume of seawater
     using the TEOS-10 standard. Ocean Modelling.

    The software is available from http://www.TEOS-10.org