# gsw_CT_freezing_poly

    Conservative Temperature freezing point (poly)

## Contents

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

## USAGE:

    CT_freezing = gsw_CT_freezing_poly(SA,p,saturation_fraction)

## DESCRIPTION:

    Calculates the Conservative Temperature at which seawater freezes.
    The error of this fit ranges between -5e-4 K and 6e-4 K when compared
    with the Conservative Temperature calculated from the exact in-situ
    freezing temperature which is found by a Newton-Raphson iteration of the
    equality of the chemical potentials of water in seawater and in ice.
    Note that the Conservative temperature freezing temperature can be found
    by this exact method using the function gsw_CT_freezing.

    Click for a more detailed description of calculating
    Conservative Temperature freezing.

## INPUT:

    SA  =  Absolute Salinity                                        [ g/kg ]
    p   =  sea pressure                                             [ dbar ]
           ( i.e. absolute pressure - 10.1325 dbar )

    OPTIONAL:

    saturation_fraction  =  the saturation fraction of dissolved air
                            in seawater
    (i.e., saturation_fraction must be between 0 and 1, and the
    default is 0, air free)

    p & saturation_fraction (if provided) may have dimensions 1x1 or Mx1
    or 1xN or MxN, where SA is MxN.

## OUTPUT:

    CT_freezing = Conservative Temperature at freezing of seawater [ deg C ]
                  That is, the freezing temperature expressed in
                  terms of Conservative Temperature (ITS-90).

## EXAMPLE:

    SA = [34.7118; 34.8915; 35.0256; 34.8472; 34.7366; 34.7324;]
    p =  [     10;      50;     125;     250;     600;    1000;]
    saturation_fraction = 1;

    CT_freezing = gsw_CT_freezing_poly(SA,p,saturation_fraction)

    CT_freezing =

      -1.899657519404743
      -1.940781208575193
      -2.006256923078589
      -2.092413889940425
      -2.359438414203326
      -2.677347349358548

## AUTHOR:

    Paul Barker, Trevor McDougall and Rainer Feistal   [ 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 section 3.3 of this TEOS-10 Manual.

    McDougall, T.J., P.M. Barker, R. Feistel and B.K. Galton-Fenzi, 2014:
     Melting of Ice and Sea Ice into Seawater and Frazil Ice Formation.
     Journal of Physical Oceanography, 44, 1751-1775.

    McDougall, T.J. and S.J. Wotherspoon, 2014: A simple modification of
     Newton’s method to achieve convergence of order "1 + sqrt(2)". Applied
     Mathematics Letters, 29, 20-25.
     http://dx.doi.org/10.1016/j.aml.2013.10.008

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