Second Derivatives of Enthalpy

Usage

gsw_enthalpy_second_derivatives(SA, CT, p)

Arguments

SA: Absolute Salinity [ g/kg ]. The valid range for most `gsw` functions is 0 to 42 g/kg.
CT: Conservative Temperature [ degC ].
p: sea pressure [dbar], i.e. absolute pressure [dbar] minus 10.1325 dbar

Value

A list containing h_SA_SA [ (J/kg)/(g/kg)^2 ], the second derivative of enthalpy with respect to Absolute Salinity, h_SA_CT [ (J/kg)/(K*g/kg) ], the derivative of enthalpy with respect to Absolute Salinity and Conservative Temperature, and h_CT_CT [ (J/kg)/degC^2 ], the second derivative of enthalpy with respect to Conservative Temperature.

Implementation Note

This R function uses a wrapper to a C function contained within the GSW-C system as updated 2022-10-11 at https://github.com/TEOS-10/GSW-C with git commit `657216dd4f5ea079b5f0e021a4163e2d26893371`.

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.

References

http://www.teos-10.org/pubs/gsw/html/gsw_enthalpy_second_derivatives.html

Examples

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)
r <- gsw_enthalpy_second_derivatives(SA, CT, p)
stopifnot(all.equal(r$h_SA_SA, c(0.000080922482023, 0.000404963500641, 0.001059800046742,
                                 0.002431088963823, 0.006019611828423, 0.010225411250217)))
stopifnot(all.equal(r$h_SA_CT, c(0.000130004715129, 0.000653614489248, 0.001877220817849,
                                 0.005470392103793, 0.014314756132297, 0.025195603327700)))
stopifnot(all.equal(r$h_CT_CT, c(0.000714303909834, 0.003584401249266, 0.009718730753139,
                                 0.024064471995224, 0.061547884081343, 0.107493969308119)))