# 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 and Preformed Salinity from
    Practical Salinity.

## INPUT:

    SP   =  Practical Salinity  (PSS-78)                        [ unitless ]
    p    =  sea pressure                                            [ dbar ]
            ( i.e. 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.
    ( i.e. 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 =

      34.711778344814128
      34.891522618230113
      35.025544862476934
      34.847229026189602
      34.736628474576065
      34.732363065590860

    Sstar =

      34.711553680880783
      34.891161395333768
      35.024650265047384
      34.843593141519371
      34.729033995955540
      34.719675962471797

    in_ocean =

       1
       1
       1
       1
       1
       1

## AUTHOR:

    Paul Barker & Trevor McDougall                     [ help@teos-10.org ]

## VERSION NUMBER:

    3.02 (7th January, 2013)

## 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, F.J. Millero, R. Pawlowicz and
     P.M. Barker, 2012: A global algorithm for estimating Absolute Salinity.
     Ocean Science, 8, 1123-1134.
      http://www.ocean-sci.net/8/1123/2012/os-8-1123-2012.pdf

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