# gsw_SP_from_R

`Practical Salinity from conductivity ratio,R`

## USAGE:

`SP = gsw_SP_from_R(R,t,p)`

## DESCRIPTION:

```Calculates Practical Salinity, SP, from the conductivity ratio, R,
primarily using the PSS-78 algorithm.  Note that the PSS-78 algorithm
for Practical Salinity is only valid in the range 2 < SP < 42.  If the
PSS-78 algorithm produces a Practical Salinity that is less than 2 then
the Practical Salinity is recalculated with a modified form of the
Hill et al. (1986) formula.  The modification of the Hill et al. (1986)
expression are to ensure that it is exactly consistent with PSS-78
at SP = 2. ``` ```Click for a more detailed description of calculating Practical Salinity from conductivity ratio.```

## INPUT:

```R  =  Conductivity ratio                                    [ unitless ]
t  =  in-situ temperature (ITS-90)                             [ deg C ]
p  =  sea pressure                                              [ dbar ]
( ie. absolute pressure - 10.1325 dbar )```
`t & p may have dimensions 1x1 or Mx1 or 1xN or MxN, where R is MxN.`

## OUTPUT:

`SP  =  Practical Salinity on the PSS-78 scale               [ unitless ]`

## EXAMPLE:

```R = [ 1.3145;  1.3123;  1.1807;  0.8886; 0.8169; 0.7687;]
t = [28.7856; 28.4329; 22.8103; 10.2600; 6.8863; 4.4036;]
p = [     10;      50;     125;     250;    600;   1000;]```
`SP = gsw_SP_from_R(R,t,p)`
`SP =`
```  34.547219254816596
34.727400381174370
34.859100827188712
34.679845200922003
34.567856165219020
34.561679175326645```

## AUTHOR:

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

## VERSION NUMBER:

`3.05 (16th February, 2015)`

## REFERENCES:

```Hill, K.D., T.M. Dauphinee and D.J. Woods, 1986: The extension of the
Practical Salinity Scale 1978 to low salinities. IEEE J. Oceanic Eng.,
OE-11, 1, 109 - 112.```
```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 appendix E of this TEOS-10 Manual.```
```Unesco, 1983: Algorithms for computation of fundamental properties of
seawater. Unesco Technical Papers in Marine Science, 44, 53 pp.```
`The software is available from http://www.TEOS-10.org`