Contents
USAGE:
[geo_strf_McD_Klocker_pc, p_mid, in_funnel] = gsw_geo_strf_McD_Klocker_pc(SA,CT,delta_p,gamma_n,layer_indx,A)
DESCRIPTION:
Calculates the McDougall-Klocker geostrophic streamfunction
(see Eqn. (3.30.1) of IOC et al. (2010)). This function is to used
when the Absolute Salinity and Conservative Temperature are piecewise
constant in the vertical over sucessive pressure intervals of delta_p
(such as in a forward "z-coordinate" ocean model, and in isopycnal
layered ocean models). The McDougall-Klocker geostrpohic streamfunction
is designed to be used as the geostrophic streamfunction in an
approximately neutral surface (such as a Neutral Density surface,
a potential density surface or an omega surface (Klocker et al. (2009)).
Reference values of Absolute Salinity, Conservative Temperature and
pressure are found by interpolation of a one-dimensional look-up table,
with the interpolating variable being Neutral Density (gamma_n) or
sigma_2.
INPUT:
SA = Absolute Salinity [ g/kg ]
CT = Conservative Temperature [ deg C ]
delta_p = difference in sea pressure between the deep and shallow
extents of each layer in which SA and CT are vertically
constant. delta_p must be positive. [ dbar ]
Note. Sea pressure is absolute pressure minus 10.1325 dbar.
gamma_n = Neutral Density anomaly [ kg/m^3 ]
(i.e. Neutral Density minus 1000 kg/m^3)
layer_indx = Index of the layers of the gamma_n surfaces
OPTIONAL:
A = if nothing is entered the programme defaults to "Neutral
Density" as the vertical interpolating variable.
= 's2' or 'sigma2', for sigma_2 as the vertical interpolating
variable.
SA, CT & delta_p need to have the same dimensions.
gamma_n & layer_indx need to have the same dimensions, there should be
only one "gamma_n" or "sigma_2" value per level of interest.
A needs to be 1x1.
OUTPUT:
geo_strf_McD_Klocker_pc = McDougall & Klocker (2010) [ m^2/s^2 ]
geostrophic streamfunction
p_mid = mid-point pressure in each layer [ dbar ]
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;]
delta_p = [ 10; 40; 75; 125; 350; 400;]
gamma_n = [26.7; 27.8;]
layer_indx = [ 3; 5;]
[geo_strf_McD_Klocker_pc, p_mid, in_funnel] = ...
gsw_geo_strf_McD_Klocker_pc(SA,CT,delta_p,gamma_n,layer_indx)
geo_strf_McD_Klocker_pc =
-5.2753
-10.3684
p_mid =
87.5000
425.0000
in_funnel =
1
1
AUTHOR:
Trevor McDougall and Paul Barker [ help_gsw@csiro.au ]
VERSION NUMBER:
2.0 (17th September, 2010)
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 the TEOS-10 web site.
See section 3.30 of this TEOS-10 Manual.
Jackett, D. R. and T. J. McDougall, 1997: A neutral density variable
for the world’s oceans. Journal of Physical Oceanography, 27, 237-263.
Klocker, A., T. J. McDougall and D. R. Jackett, 2009: A new method
for forming approximately neutral surfaces. Ocean Sci., 5, 155-172.
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.
McDougall, T. J. and A. Klocker, 2010: An approximate geostrophic
streamfunction for use in density surfaces. Ocean Modelling, 32,
105-117.
The McDougall-Klocker geostrophic streamfunction is defined in
Eqn. (62) of this paper.
See section 8 of this paper for a discussion of this piecewise-
constant version of the McDougall-Klocker geostrophic streamfunction.
The software is available from http://www.TEOS-10.org