# gsw_SA_CT_plot

    plots Absolute Salinity - Conservative Temperature
    profiles on a SA-CT diagram including freezing line and
    selected potential density contours.(48-term equation)

## Contents

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

## USAGE:

    gsw_SA_CT_plot(SA,CT,p_ref,isopycs,title_string)

## DESCRIPTION:

    Produces a plot of Absolute Salinity - Conservative Temperature
    profiles.  The diagram also plots the Conservative Temperature freezing
    point for p = 0 dbar assuming the seawater is completely saturated with
    dissolved air and user defined potential density contours.  This
    function uses the computationally efficient 48-term expression for
    density in terms of SA, CT and p (McDougall et al., 2011).

    Note that the 48-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. (2011).  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".

## INPUT:

##

    SA    =  Absolute Salinity                                     [ g/kg ]
    CT    =  Conservative Temperature                             [ deg C ]
    p     =  sea pressure                                          [ dbar ]
             ( i.e. absolute pressure - 10.1325 dbar )
    Optional:
    p_ref        = reference sea pressure for the isopycnals        [ dbar ]
                   (i.e. absolute reference pressure - 10.1325 dbar)
                   If it is not suppled a default of 0 dbar is used.
    isopycs      = isopycnals, can be either an array of isopynals or the
                   number of isopynals to appear on the plot.  If it is not
                   supplied the programme defaults to 5 isopynals.
    title_string = title text to appear at the top of the plot.

    SA & CT need to have the same dimensions.
    p_ref should be a scalar, (i.e. have dimensions 1x1).
    isopycs can be either 1x1 or 1xN or Mx1

## 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;]
    p_ref = 1000
    isopycs = [24:0.5:33];

    gsw_SA_CT_plot(SA,CT,p_ref,isopycs,'\it{S}\rm_A - {\Theta} diagram')

## AUTHOR:

    Rich Pawlowicz                                 [ help@teos-10.org ]
    Note. This function was extracted and adapted from Rich Pawlowicz's
     ocean toolbox.

    Modified:

    Paul Barker & Trevor McDougall

## VERSION NUMBER:

    3.01 (16th May, 2011).

## 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.

    McDougall T.J., P.M. Barker, R. Feistel and D.R. Jackett, 2011:  A
     computationally efficient 48-term expression for the density of
     seawater in terms of Conservative Temperature, and related properties
     of seawater.  To be submitted to Ocean Science Discussions.

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