gsw_enthalpy_first_derivatives: First Derivatives of Enthalpy

View source: R/gsw.R

gsw_enthalpy_first_derivativesR Documentation

First Derivatives of Enthalpy


First Derivatives of Enthalpy


gsw_enthalpy_first_derivatives(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.

Implementation Note

This R function uses a wrapper to a C function contained within the GSW-C system as updated 2021-12-28 at 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 website. Therefore, in the interests of making GSW-R be self-contained, a copy was downloaded from on 2022-05-25, the .mat file was stored in the developer/create_data directory of, and then the dataset used in GSW-R was created based on that .mat file.

Please consult to learn more about the various TEOS-10 software systems.


See Also

Other things related to enthalpy: gsw_CT_from_enthalpy(), gsw_dynamic_enthalpy(), gsw_enthalpy_CT_exact(), gsw_enthalpy_diff(), gsw_enthalpy_first_derivatives_CT_exact(), 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(SA, CT, p)
stopifnot(all.equal(d$h_SA, c(-0.070223912348929, -0.351159768365102, -0.887025065692568,
                              -1.829602387915694, -4.423463748270238, -7.405100077558673)))
stopifnot(all.equal(d$h_CT/1e3, c(3.991899705530481, 3.992025640520101, 3.992210365030743,
                                  3.992284150250490, 3.992685389122658, 3.993014168534175)))

gsw documentation built on Oct. 16, 2022, 5:06 p.m.