# gsw_rho_alpha_beta_CT25

    In-situ density, thermal expansion & saline
    contraction coefficient (25-term equation)

## Contents

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

## USAGE:

    [rho, alpha_CT, beta_CT, in_funnel] = gsw_rho_alpha_beta_CT25(SA,CT,p)

## DESCRIPTION:

    Calculates in-situ density, the appropiate thermal expansion coefficient
    and the appropriate saline contraction coefficient of seawater from
    Absolute Salinity and Conservative Temperature.  This function uses the
    computationally-efficient 25-term expression for density in terms of
    SA, CT and p (McDougall et al., 2010).

    Note that potential density (pot_rho) with respect to reference pressure
    pr is obtained by calling this function with the pressure argument being
    pr as in [pot_rho, ~, ~, in_funnel] = gsw_rho_alpha_beta_CT25(SA,CT,pr).

    Click for a more detailed description of rho, alpha_CT
    and beta_CT.

## INPUT:

    SA  =  Absolute Salinity                                        [ g/kg ]
    CT  =  Conservative Temperature                                [ deg C ]
    p   =  sea pressure                                             [ dbar ]
           (ie. absolute pressure - 10.1325 dbar)

    SA & CT need to have the same dimensions.
    p may have dimensions 1x1 or Mx1 or 1xN or MxN, where SA & CT are MxN.

## OUTPUT:

    rho       =   in-situ density                                [ kg m^-3 ]
    alpha_CT  =   thermal expansion coefficient                      [ 1/K ]
                  with respect to Conservative Temperature
    beta_CT   =   saline contraction coefficient                    [ kg/g ]
                  at constant Conservative Temperature
    in_funnel  =  0, if SA, CT and p are outside the "funnel"
               =  1, if SA, CT and p are inside the "funnel"
    Note. The term "funnel" describes the range of SA, CT and p over which
      the error in the fit of the computationally-efficient 25-term
      expression for density was calculated (McDougall et al., 2010).

## 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;]
    p =  [     10;      50;     125;     250;     600;    1000;]

    [rho, alpha_CT, beta_CT, in_funnel] = gsw_rho_alpha_beta_CT25(SA,CT,p)

    rho =

    1.0e+003 *

     1.021839541498949
     1.022261845123599
     1.024426245497197
     1.027792152543827
     1.029838876568916
     1.032002445797635

    alpha_CT =

    1.0e-003 *

     0.324356899200044
     0.322411511462120
     0.281313314947018
     0.173211327216534
     0.146078398825498
     0.129148950914940

    beta_CT =

    1.0e-003 *

     0.717340839421976
     0.717514858800028
     0.726299524800543
     0.750622769257820
     0.755000880950473
     0.756865290355974

    in_funnel =

       1
       1
       1
       1
       1
       1

## AUTHOR:

    David Jackett, Trevor McDougall and Paul Barker   [ help_gsw@csiro.au ]

## VERSION NUMBER:

    2.0 (23rd July, 2010)

## 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 appendix A.20 and appendix K of this TEOS-10 Manual.

    McDougall T. J., D. R. Jackett, P. M. Barker, C. Roberts-Thomson, R.
     Feistel and R. W. Hallberg, 2010:  A computationally efficient 25-term
     expression for the density of seawater in terms of Conservative
     Temperature, and related properties of seawater.  To be submitted
     to Ocean Science Discussions.

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