First Derivatives of Potential Temperature

Usage

gsw_pt_first_derivatives(SA, CT)

Arguments

SA: Absolute Salinity [ g/kg ]. The valid range for most `gsw` functions is 0 to 42 g/kg.
CT: Conservative Temperature [ degC ].

Value

A list containing pt_SA [ K/(g/kg) ], the derivative of potential temperature with respect to Absolute Salinity, and pt_CT [ unitless ], the derivative of potential temperature 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_pt_first_derivatives.html

Examples

SA <- c(34.7118, 34.8915, 35.0256, 34.8472, 34.7366, 34.7324)
CT <- c(28.8099, 28.4392, 22.7862, 10.2262,  6.8272,  4.3236)
r <- gsw_pt_first_derivatives(SA, CT)
stopifnot(all.equal(r$pt_SA, c(0.041863223165431, 0.041452303483011, 0.034682095247246,
                               0.018711079068408, 0.014079958329844, 0.010577326129948)))
stopifnot(all.equal(r$pt_CT, c(0.997192967140242, 0.997451686508335, 0.998357568277750,
                               0.999996224076267, 1.000283719083268, 1.000525947028218)))