gsw_geo_strf_Cunningham

Cunningham geostrophic streamfunction

Contents

USAGE:

[geo_strf_Cunningham, in_funnel] = gsw_geo_strf_Cunningham(SA,CT,p,interp_style)

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 at the sea surface.  This function
calculates specific volume anomaly using the computationally efficient
25-term expression for specific volume of McDougall et al. (2010).
Under the default setting, this function evaluates the pressure integral
of specific volume using SA and CT “interploted” with respect to pressure
using a scheme based on the method of Reiniger and Ross (1968).  Our 
method uses a weighted mean of (i) values obtained from linear 
interpolation of the two nearest data points, and (ii) a linear 
extrapolation of the pairs of data above and below. This "curve fitting"
method resembles the use of cubic splines.  If the option “linear” is 
chosen, the function interpolates Absolute Salinity and Conservative 
Temperature linearly with presure in the vertical between “bottles”.
TEOS-10
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 ]
       ( ie. absolute pressure - 10.1325 dbar )
OPTIONAL:
interp_style = interpolation technique.
             = if nothing is entered the programme defaults to "curved" 
               interpolation between bottles in the vertical.
             = if "linear" or "lin" is entered then the programme 
               interpolates linearly between bottles in the
               vertical.
SA & CT need to have the same dimensions.
p may have dimensions Mx1 or 1xN or MxN, where SA & CT are MxN.

OUTPUT:

geo_strf_Cunningham = Cunningham geostrophic streamfunction  [ m^2/s^2 ]
in_funnel           = 0, if SA, CT and p are outside the "funnel"
                    = 1, if SA, CT and p are inside the "funnel"
Note. The term "funnel" describes the range of SA, CT and p over which
  the error in the fit of the computationally-efficient 25-term
  expression for density was calculated (McDougall et al., 2010).

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;]
[geo_strf_Cunningham, in_funnel] = gsw_geo_strf_Cunningham(SA,CT,p)
geo_strf_Cunningham =             in_funnel =
   0.6007                             1
  -0.0151                             1
  -1.6280                             1
  -6.5022                             1
  -8.3101                             1
 -10.7625                             1

AUTHOR:

 Trevor McDougall and Paul Barker [ help_gsw@csiro.au ]

VERSION NUMBER:

2.0 (26th August, 2010)

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., D.R. Jackett, P.M. Barker, C. Roberts-Thomson, R.
 Feistel and R.W. Hallberg, 2010:  A computationally efficient 25-term
 expression for the density of seawater in terms of Conservative
 Temperature, and related properties of seawater.  To be submitted
 to Ocean Science Discussions.
The software is available from http://www.TEOS-10.org