gsw_CT_first_derivatives_wrt_t_exact function

Derivatives of Conservative Temperature with Respect to or at Constant in-situ Temperature

gsw_CT_first_derivatives_wrt_t_exact(SA, t, p)

Arguments

• SA: Absolute Salinity [ g/kg ]. The valid range for most gsw functions is 0 to 42 g/kg.
• t: in-situ temperature (ITS-90) [ degC ]
• p: sea pressure [dbar], i.e. absolute pressure [dbar] minus 10.1325 dbar

Returns

A list containing CT_SA_wrt_t [ K/(g/kg) ], the derivative of Conservative Temperature with respect to Absolute Salinity at constant temperature and pressure, CT_t_wrt_t [ unitless], the derivative of Conservative Temperature with respect to temperature at constant Absolute Salinity and pressure, and CT_p_wrt_t, the derivative of Conservative Temperature with respect to pressure at constant Absolute Salinity and 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.

Examples

SA <- c(34.7118, 34.8915, 35.0256, 34.8472, 34.7366, 34.7324)
t <- c( 28.7856, 28.4329, 22.8103, 10.2600,  6.8863,  4.4036)
p <- c(      10,      50,     125,     250,     600,    1000)
r <- gsw_CT_first_derivatives_wrt_t_exact(SA, t, p)
stopifnot(all.equal(r$CT_SA_wrt_t,
    c(-0.041988694538987, -0.041596549088952, -0.034853545749326,
      -0.019067140454607, -0.015016439826591, -0.012233725491373)))
stopifnot(all.equal(r$CT_t_wrt_t,
    c(1.002752642867571, 1.002243118597902, 1.000835702767227,
      0.998194915250648, 0.995219303532390, 0.991780205482695)))
stopifnot(all.equal(r$CT_p_wrt_t/1e-7,
    c(-0.241011880838437, -0.239031676279078, -0.203649928441505,
      -0.119370679226136, -0.099140832825342, -0.086458168643579)))

References

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