gsw_enthalpy_first_derivatives

first derivatives of enthalpy (75-term equation)

Contents

USAGE:

[h_SA, h_CT] = gsw_enthalpy_first_derivatives(SA,CT,p)

DESCRIPTION:

Calculates the following two derivatives of specific enthalpy (h),
of seawater using the computationally-efficient 75-term expression 
for specific volume in terms of SA, CT and p (Roquet et al., 2015).  
 (1) h_SA, the derivative with respect to Absolute Salinity at
     constant CT and p, and
 (2) h_CT, derivative with respect to CT at constant SA and p.
Note that the 75-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. (2003).  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".
TEOS-10 
Click for a more detailed description of the first
derivatives of specific enthalpy.

INPUT:

SA  =   Absolute Salinity                                       [ g/kg ]
CT  =   Conservative Temperature                               [ deg C ]
p   =   sea pressure                                            [ dbar ]
        (i.e. absolute pressure - 10.1325 dbar)
SA & CT need to have the same dimensions.
p may have dimensions 1x1 or Mx1 or 1xN or MxN, where SA & CT are MxN.

OUTPUT:

h_SA   =  The first derivative of specific enthalpy with respect to
          Absolute Salinity at constant CT and p.
                                          [ J/(kg (g/kg))]  i.e. [ J/g ]
h_CT   =  The first derivative of specific enthalpy with respect to
          CT at constant SA and p.                          [ J/(kg K) ]

EXAMPLE:

SA = [34.7118; 34.8915; 35.0256; 34.8472; 34.7366; 34.7324;]
CT =  [28.7856; 28.4329; 22.8103; 10.2600;  6.8863;  4.4036;]
p =  [     10;      50;     125;     250;     600;    1000;]
[h_SA, h_CT] = gsw_enthalpy_first_derivatives(SA,CT,p)
h_SA =
  -0.070223912348929
  -0.351159768365102
  -0.887025065692568
  -1.829602387915694
  -4.423463748270238
  -7.405100077558673
h_CT =
1.0e+003 *
   3.991899705530481
   3.992025640520101
   3.992210365030743
   3.992284150250490
   3.992685389122658
   3.993014168534175

AUTHOR:

Trevor McDougall.                      [ help@teos-10.org ]

VERSION NUMBER:

3.05.6 (20th March, 2017)

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. (A.11.18), (A.11.15) and (A.11.12) of this TEOS-10 Manual.
McDougall, T.J., D.R. Jackett, D.G. Wright and R. Feistel, 2003: 
 Accurate and computationally efficient algorithms for potential 
 temperature and density of seawater.  J. Atmosph. Ocean. Tech., 20,
 pp. 730-741.
Roquet, F., G. Madec, T.J. McDougall and P.M. Barker, 2015: Accurate
 polynomial expressions for the density and specific volume of seawater 
 using the TEOS-10 standard.  Ocean Modelling, 90, pp. 29-43. 
 http://dx.doi.org/10.1016/j.ocemod.2015.04.002
This software is available from http://www.TEOS-10.org