# gsw_Fdelta

`ratio of Absolute to Preformed Salinity, minus 1`

## USAGE:

`Fdelta = gsw_Fdelta(p,long,lat)`

## DESCRIPTION:

```Calculates Fdelta from the Absolute Salinity Anomaly
Ratio (SAAR). It finds SAAR by calling the function
"gsw_SAAR(p,long,lat") and then simply calculates Fdelta from

Fdelta = (1 + r1)SAAR/(1 - r1*SAAR)
= (SA/Sstar) - 1

with r_1 being the constant 0.35 based on the work of Pawlowicz
et al. (2011). Note that since SAAR is everywhere less than
0.001 in the global ocean, Fdelta is only slighty different to
"1.35 x SAAR".```
 ```Click for a more detailed description of the ratio of Absolute to Preformed Salinity, minus 1 (Also see the description of Absolute Salinity Amomaly Ratio).```

## INPUT:

```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, long & lat need to have the same dimensions.`

## OUTPUT:

`Fdelta = ratio of Absolute to Preformed Salinity, minus 1   [ unitless ]`

## EXAMPLE:

```p =    [   10;   50;  125;  250;  600; 1000;]
lat =  [    4;    4;    4;    4;    4;    4;]
long = [  188;  188;  188;  188;  188;  188;]```
`Fdelta = gsw_Fdelta(p,long,lat)`
`Fdelta = `
`  1.0e-003 *`
```   0.006472309923452
0.010352848168433
0.025541937543450
0.104348729347986
0.218678084205081
0.365415366571266```

## AUTHOR:

`Trevor McDougall and Paul Barker       [ 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 http://www.TEOS-10.org
See section 2.5 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`