# gsw_SA_Sstar_from_SP

    Absolute Salinity and Preformed Salinity from
    Practical Salinity

## Contents

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

## USAGE:

    [SA, Sstar, in_ocean] = gsw_SA_Sstar_from_SP(SP,p,long,lat)

## DESCRIPTION:

    Calculates Absolute Salinity and Preformed Salinity from Practical
    Salinity.  Since SP is non-negative by definition, this function
    changes any negative input values of SP to be zero.

    Click for a more detailed description of calculating
    Absolute Salinity from Practical Salinity.
    Click for a more detailed description of calculating
    Preformed Salinity from Practical Salinity.

## INPUT:

    SP   =  Practical Salinity  (PSS-78)                        [ unitless ]
    p    =  sea pressure                                            [ dbar ]
           ( ie. absolute pressure - 10.1325 dbar )
    long  = longitude in decimal degrees                      [ 0 ... +360 ]
                                                       or  [ -180 ... +180 ]
    lat  =  latitude in decimal degrees north                [ -90 ... +90 ]

    p, lat & long may have dimensions 1x1 or Mx1 or 1xN or MxN,
    where SP is MxN.

## OUTPUT:

    SA        =  Absolute Salinity                                  [ g/kg ]
    Sstar     =  Preformed Salinity                                 [ g/kg ]
    in_ocean  =  0, if long and lat are a long way from the ocean
              =  1, if long and lat are in the ocean
      Note. This flag is only set when the observation is well and truly on
        dry land; often the warning flag is not set until one is several
        hundred kilometres inland from the coast.

## EXAMPLE:

    SP =   [34.5487; 34.7275; 34.8605; 34.6810; 34.5680; 34.5600;]
    p =    [     10;      50;     125;     250;     600;    1000;]
    lat =  [      4;       4;       4;       4;       4;       4;]
    long = [    188;     188;     188;     188;     188;     188;]

    If the profile data refers to one location (one station) is it
    acceptable to enter the station location once.
    (ie the following will produce the same result as the input above).

    SP =   [34.5487; 34.7275; 34.8605; 34.6810; 34.5680; 34.5600;]
    p =    [     10;      50;     125;     250;     600;    1000;]
    lat =   4;
    long = 188;

    [SA, Sstar, in_ocean] = gsw_SA_Sstar_from_SP(SP,p,long,lat)

    SA =

      34.711779712893147
      34.891523721622328
      35.025547737221643
      34.847230081708567
      34.736629598766619
      34.732361864645107

    Sstar =

      34.711553202053111
      34.891161009146472
      35.024649258886718
      34.843592772087710
      34.729033602488833
      34.719676382802788

    in_ocean =

       1
       1
       1
       1
       1
       1

## AUTHOR:

    David Jackett, Trevor McDougall & 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 section 2.5 and appendices A.4 and A.5 of this TEOS-10 Manual.

    McDougall, T.J., D.R. Jackett and F.J. Millero, 2010: An algorithm
     for estimating Absolute Salinity in the global ocean.  Submitted to
     Ocean Science. A preliminary version is available at Ocean Sci. Discuss.,
     6, 215-242.
     http://www.ocean-sci-discuss.net/6/215/2009/osd-6-215-2009-print.pdf

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