Contents
USAGE:
[G_CT, p_mid] = gsw_isopycnal_vs_ntp_CT_ratio(SA,CT,p,p_ref)
DESCRIPTION:
Calculates the ratio of the two-dimensional gradient of Conservative
Temperature in a potential density surface (with reference sea pressure
(p_ref)) versus that in the neutral tangent plane (ntp) (see Eqns. (3.17.3)
and (3.17.4) of IOC et al. (2010)). This ratio has been called the
"isopycnal Conservative Temperature gradient ratio". This ratio is
evaluated at the mid pressure between the individual data points in the
vertical. The reference sea pressure of the potential density surface
must have a constant value. This function uses from the computationally
efficient 48-term expression for density in terms of SA, CT and p
(McDougall et al., 2011).
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 sea pressure of the potential density surface
( i.e. reference absolute pressure - 10.1325 dbar ) [ dbar ]
SA & CT need to have the same dimensions.
p & pr may have dimensions 1x1 or Mx1 or 1xN or MxN, where SA & CT
are MxN
OUTPUT:
G_CT = The ratio of the gradient of CT in a potential density surface
to that in a neutral tangent plane. G_CT is output on the
same vertical (M-1)xN grid as p_mid, where M & N are the
dimensions of SA. G_CT is dimensionless. [ unitless ]
p_mid = mid pressure between the individual points of the p grid.
That is, p_mid is on a (M-1)xN grid. [ dbar ]
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 = 0
[G_CT, p_mid] = gsw_isopycnal_vs_ntp_CT_ratio(SA,CT,p,p_ref)
G_CT =
1.000630863388660
1.004179196949259
1.016635934710221
1.080042249305421
1.174924051056580
p_mid =
1.0e+002 *
0.300000000000000
0.875000000000000
1.875000000000000
4.250000000000000
8.000000000000000
AUTHOR:
Trevor McDougall, Paul Barker & David Jackett [ 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 the TEOS-10 web site.
See Eqns. (3.17.3) and (3.17.4) of this TEOS-10 Manual.
McDougall, T. J., 1987: Neutral surfaces. Journal of Physical
Oceanography, 17, 1950-1964. See Eqn. (29) of this paper.
McDougall T.J., P.M. Barker, R. Feistel and D.R. Jackett, 2011: 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 Ocean Science Discussions.
The software is available from http://www.TEOS-10.org