# gsw_geo_strf_Cunningham

    Cunningham geostrophic streamfunction

## Contents

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

## USAGE:

    geo_strf_Cunningham = gsw_geo_strf_Cunningham(SA,CT,p,p_ref)

## DESCRIPTION:

    Calculates the Cunningham geostrophic streamfunction (see Eqn. (3.29.2)
    of IOC et al. (2010)).  This is the geostrophic streamfunction for the
    difference between the horizontal velocity at the pressure concerned,
    p, and the horizontal velocity on the pressure surface, p_ref.  This
    function calculates specific volume anomaly using the computationally
    efficient 48-term expression for specific volume of McDougall et al. (2013).

    Note that p_ref, is the reference pressure to which the streamfunction
    is referenced.  When p_ref is zero, "gsw_geo_strf_Cunningham" returns
    the Cunningham geostrophic streamfunction with respect to the sea
    surface, otherwise, the function returns the geostrophic streamfunction
    with respect to the (deep) reference pressure p_ref.

    Note that the 48-term equation has been fitted in a restricted range of
    parameter space, and is most accurate inside the "oceanographic funnel"
    described in McDougall et al. (2013).  The GSW library function
    "gsw_infunnel(SA,CT,p)" is avaialble to be used if one wants to test if
    some of one's data lies outside this "funnel".

    Click for a more detailed description of the Cunningham
    streamfunction.

## INPUT:

    SA   =  Absolute Salinity                                       [ g/kg ]
    CT   =  Conservative Temperature                               [ deg C ]
    p    =  sea pressure                                            [ dbar ]
            ( i.e. absolute pressure - 10.1325 dbar )
    p_ref = reference pressure                                      [ dbar ]
            ( i.e. reference absolute pressure - 10.1325 dbar )

    SA & CT need to have the same dimensions.
    p may have dimensions Mx1 or 1xN or MxN, where SA & CT are MxN.
    p_ref needs to be a single value, it can have dimensions 1x1 or Mx1 or
    1xN or MxN.

## OUTPUT:

    geo_strf_Cunningham = Cunningham geostrophic streamfunction  [ m^2/s^2 ]

## EXAMPLE:

    SA = [34.7118; 34.8915; 35.0256; 34.8472; 34.7366; 34.7324;]
    CT = [28.8099; 28.4392; 22.7862; 10.2262;  6.8272;  4.3236;]
    p =  [     10;      50;     125;     250;     600;    1000;]
    p_ref = 1000

    geo_strf_Cunningham = gsw_geo_strf_Cunningham(SA,CT,p,p_ref)

    geo_strf_Cunningham =

      17.893004502475378
      17.819966326875146
      16.224154546318459
      11.382163183421653
       9.576877475752553
       7.122260539475974

## AUTHOR:

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

## VERSION NUMBER:

    3.02 (17th November, 2012)

## REFERENCES:

    Cunningham, S.A., 2000: Circulation and volume flux of the North
     Atlantic using syoptic hydrographic data in a Bernoulli inverse.
     J. Marine Res., 58, 1-35.

    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 3.29 of this TEOS-10 Manual.

    McDougall T.J., P.M. Barker, R. Feistel and D.R. Jackett, 2013:  A
     computationally efficient 48-term expression for the density of
     seawater in terms of Conservative Temperature, and related properties
     of seawater.  To be submitted to J. Atm. Ocean. Technol., xx, yyy-zzz.

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