[h_SA, h_CT, h_P] = gsw_enthalpy_first_derivatives(SA,CT,p)
Calculates the following three derivatives of specific enthalpy (h)
(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.
(3) h_P, derivative with respect to pressure (in Pa) at constant
SA and CT.
Note that this function uses the full Gibbs function. There is an
alternative to calling this function, namely
gsw_enthalpy_first_derivatives(SA,CT,p),which uses the computationally
efficient 75-term expression for specific volume in terms of SA, CT and
p (Roquet et al., 2015).
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.
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) ]
h_P = The first partial derivative of specific enthalpy with
respect to pressure (in Pa) at fixed SA and CT. Note that
h_P is specific volume (1/rho). [ m^3/kg ]
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_CT_exact(SA,CT,p)
Trevor McDougall. [ email@example.com ]
3.05 (16th February, 2015)
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.
Roquet, F., G. Madec, T.J. McDougall, P.M. Barker, 2015: Accurate
polynomial expressions for the density and specifc volume of seawater
using the TEOS-10 standard. Ocean Modelling.
This software is available from http://www.TEOS-10.org