# gsw_SA_Sstar_from_SP

```Absolute Salinity and Preformed Salinity from
Practical Salinity```

## 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:

`3.05 (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 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`