Specific Entropy i.t.o. Absolute Salinity, Temperature, and Pressure

Calculates specific entropy in terms of Absolute Salinity, in-situ temperature and pressure.

gsw_entropy_from_t(SA, t, p)

Arguments

SA

Absolute Salinity [ g/kg ]

t

in-situ temperature (ITS-90) [ degC ]

p

sea pressure [dbar], i.e. absolute pressure [dbar] minus 10.1325 dbar

Value

specific entropy [ J/(kg*K) ]

Implementation Note

This R function uses a wrapper to a C function contained within the GSW-C system as updated 2021-12-28 at https://github.com/TEOS-10/GSW-C 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 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_entropy_from_t.html

See also

Other things related to entropy: gsw_CT_from_entropy(), gsw_entropy_first_derivatives(), gsw_entropy_from_pt(), gsw_entropy_ice(), gsw_pt_from_entropy()

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)
e <- gsw_entropy_from_t(SA, t, p)
stopifnot(all.equal(e/1e2, c(4.003894252787245, 3.954381784340642, 3.198664981986740,
                             1.467908815899072, 0.986473408657975, 0.627915087346090)))