# gsw_Fdelta

    ratio of Absolute to Preformed Salinity, minus 1

## Contents

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

## 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
    (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:

    3.01 (23rd May, 2011)

## 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 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