gsw_sigma3 function

Potential density anomaly referenced to 3000 dbar

This uses the 75-term density equation, and returns potential density referenced to a pressure of 3000 dbar, minus 1000 kg/m^3.

gsw_sigma3(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 ].

Returns

potential density anomaly with reference pressure 3000 dbar [ kg/m^3 ]

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)
CT <- c(28.8099, 28.4392, 22.7862, 10.2262,  6.8272,  4.3236)
sigma3 <- gsw_sigma3(SA,CT)
stopifnot(all.equal(sigma3, c(34.003747849903675, 34.267409891564057, 36.316415829697917,
                              39.732367693977039, 40.397934186745033, 40.881795690566832)))

References

http://www.teos-10.org/pubs/gsw/html/gsw_sigma3.html

See Also

Other things related to density: gsw_CT_from_rho(), gsw_CT_maxdensity(), gsw_SA_from_rho(), gsw_alpha(), gsw_alpha_on_beta(), gsw_alpha_wrt_t_exact(), gsw_alpha_wrt_t_ice(), gsw_beta(), gsw_beta_const_t_exact(), gsw_infunnel(), gsw_pot_rho_t_exact(), gsw_rho(), gsw_rho_alpha_beta(), gsw_rho_first_derivatives(), gsw_rho_first_derivatives_wrt_enthalpy(), gsw_rho_ice(), gsw_rho_t_exact(), gsw_sigma0(), gsw_sigma1(), gsw_sigma2(), gsw_sigma4(), gsw_specvol(), gsw_specvol_alpha_beta(), gsw_specvol_anom_standard(), gsw_specvol_ice(), gsw_specvol_t_exact()