First Derivatives of Enthalpy wrt CT
gsw_enthalpy_first_derivatives_CT_exact(SA, CT, p)Absolute Salinity [ g/kg ]
Conservative Temperature [ degC ]
sea pressure [dbar], i.e. absolute pressure [dbar] minus 10.1325 dbar
a list containing h_SA [ (J/kg)/(g/kg) ], the derivative
of enthalpy wrt Absolute Salinity, and h_CT [ (J/kg)/degC ],
the derivative of enthalpy wrt Conservative Temperature.
This R function uses a wrapper to a C function contained within the GSW-C system as updated 2021-12-28 at https://github.com/TEOS-10/GSW-C with git commit `98f0fd40dd9ceb0ba82c9d47ac750e935a7d0459`.
The C function uses data from the library/gsw_data_v3_0.mat
file provided in the GSW-Matlab source code, version 3.06-11.
Unfortunately, this version of the mat file is no longer displayed on the
TEOS-10.org website. Therefore, in the interests of making GSW-R be
self-contained, a copy was downloaded from
http://www.teos-10.org/software/gsw_matlab_v3_06_11.zip on 2022-05-25,
the .mat file was stored in the developer/create_data directory of
https://github.com/TEOS-10/GSW-R, and then the dataset used in GSW-R
was created based on that .mat file.
Please consult http://www.teos-10.org to learn more about the various TEOS-10 software systems.
The HTML documentation suggests that this function returns 3 values, but there are only 2 returned values in the C code used here (and the matlab code on which that is based). Also, the d/dSA check values given the HTML are not reproduced by the present function. This was reported on Mar 18, 2017 as https://github.com/TEOS-10/GSW-Matlab/issues/7. See https://github.com/TEOS-10/GSW-R/issues/34
Other things related to enthalpy:
gsw_CT_from_enthalpy(),
gsw_dynamic_enthalpy(),
gsw_enthalpy_CT_exact(),
gsw_enthalpy_diff(),
gsw_enthalpy_first_derivatives(),
gsw_enthalpy_ice(),
gsw_enthalpy_t_exact(),
gsw_enthalpy(),
gsw_frazil_properties_potential_poly(),
gsw_frazil_properties_potential(),
gsw_pot_enthalpy_from_pt_ice_poly(),
gsw_pot_enthalpy_from_pt_ice(),
gsw_pot_enthalpy_ice_freezing_poly(),
gsw_pot_enthalpy_ice_freezing(),
gsw_pt_from_pot_enthalpy_ice_poly(),
gsw_pt_from_pot_enthalpy_ice(),
gsw_specvol_first_derivatives_wrt_enthalpy(),
gsw_specvol_first_derivatives()
SA <- c(34.7118, 34.8915, 35.0256, 34.8472, 34.7366, 34.7324)
CT <- c(28.7856, 28.4329, 22.8103, 10.2600, 6.8863, 4.4036)
p <- c( 10, 50, 125, 250, 600, 1000)
d <- gsw_enthalpy_first_derivatives_CT_exact(SA, CT, p)
stopifnot(all.equal(d$h_SA, c(-0.070224183838619, -0.351159869043798, -0.887036550157504,
-1.829626251448858, -4.423522691827955, -7.405211691293971)))
stopifnot(all.equal(d$h_CT/1e3, c(3.991899712269790, 3.992025674159605, 3.992210402650973,
3.992283991748418, 3.992685275917238, 3.993014370250710)))