# gsw_alpha

    thermal expansion coefficient with respect to
    Conservative Temperature. (75-term equation)

## Contents

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

## USAGE:

    alpha = gsw_alpha(SA,CT,p)

## DESCRIPTION:

    Calculates the thermal expansion coefficient of seawater with respect to
    Conservative Temperature using the computationally-efficient 75-term
    expression for specific volume in terms of SA, CT and p (Roquet et al.,
    2015).

    Note that the 75-term equation has been fitted in a restricted range of
    parameter space, and is most accurate inside the "oceanographic funnel"
    described in McDougall et al. (2003).  The GSW library function
    "gsw_infunnel(SA,CT,p)" is avaialble to be used if one wants to test if
    some of one's data lies outside this "funnel".

    Click for a more detailed description of alpha with
    respect to Conservative Temperature.

## INPUT:

    SA  =  Absolute Salinity                                          [ g/kg ]
    CT  =  Conservative Temperature (ITS-90)                         [ 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:

    alpha  =  thermal expansion coefficient                            [ 1/K ]
              with respect to Conservative Temperature

## EXAMPLE:

    SA = [34.7118; 34.8915; 35.0256; 34.8472; 34.7366; 34.7324;]
    CT = [28.7856; 28.4329; 22.8103; 10.2600;  6.8863;  4.4036;]
    p =  [     10;      50;     125;     250;     600;    1000;]

    alpha = gsw_alpha(SA,CT,p)

    alpha =

    1.0e-003 *

       0.324464211877393
       0.322610094680523
       0.281335030247435
       0.173529986885424
       0.146898108553385
       0.130265123640082

## AUTHOR:

    Paul Barker and Trevor McDougall                      [ 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. (2.18.3) of this TEOS-10 manual.

    McDougall, T.J., D.R. Jackett, D.G. Wright and R. Feistel, 2003:
     Accurate and computationally efficient algorithms for potential
     temperature and density of seawater.  J. Atmosph. Ocean. Tech., 20,
     pp. 730-741.

    Roquet, F., G. Madec, T.J. McDougall and P.M. Barker, 2015: Accurate
     polynomial expressions for the density and specific volume of seawater
     using the TEOS-10 standard.  Ocean Modelling, 90, pp. 29-43.
     http://dx.doi.org/10.1016/j.ocemod.2015.04.002

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