[h_SA_wrt_t, h_T_wrt_t, h_P_wrt_t] = ...
Calculates the following three derivatives of specific enthalpy, h.
These derivatives are done with respect to in-situ temperature t (in the
case of h_T_wrt_t) or at constant in-situ tempertature (in the cases of
h_SA_wrt_t and h_P_wrt_t).
(1) h_T_wrt_t, the derivative with respect to Absolute Salinity at
constant t and p.
(2) h_T_wrt_t, derivative with respect to in-situ temperature t at
constant SA and p.
(3) h_P_wrt_t, derivative with respect to pressure P (in Pa) at constant
SA and t. This output has the same dimensions as specific volume,
but is not equal to specific volume.
Note that this function uses the full Gibbs function. This function
avoids the Nan that would exist in h_sub_SA at SA=0 if it were
evaluated in the straightforward way from the gibbs function.
SA = Absolute Salinity [ g/kg ]
t = in-situ temperature (ITS-90) [ deg C ]
p = sea pressure [ dbar ]
(i.e. absolute pressure - 10.1325 dbar)
SA & t need to have the same dimensions.
p may have dimensions 1x1 or Mx1 or 1xN or MxN, where SA & t are MxN.
h_SA_wrt_t = The first derivative of specific enthalpy with respect to
Absolute Salinity at constant t and p.
[ J/(kg (g/kg))] i.e. [ J/g ]
h_T_wrt_t = The first derivative of specific enthalpy with respect to
in-situ temperature, t, at constant SA and p. [ J/(kg K) ]
h_P_wrt_t = The first derivative of specific enthalpy with respect to
pressure P (in Pa) at constant SA and t. [ m^3/kg ]
SA = [34.7118; 34.8915; 35.0256; 34.8472; 34.7366; 34.7324;]
t = [28.7856; 28.4329; 22.8103; 10.2600; 6.8863; 4.4036;]
p = [ 10; 50; 125; 250; 600; 1000;]
[h_SA_wrt_t, h_T_wrt_t, h_P_wrt_t] = gsw_enthalpy_first_derivatives_wrt_t_exact(SA,t,p)
Trevor McDougall and Paul Barker [ 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.
This software is available from http://www.TEOS-10.org