Second Derivatives of Entropy
gsw_entropy_second_derivatives(SA, CT)Absolute Salinity [ g/kg ]
Conservative Temperature [ degC ]
A list containing eta_SA_SA [ (J/(K*kg))/(g/kg)^2 ], the second derivative of
entropy with respect to Absolute Salinity, eta_SA_CT [ (J/(K*kg))/(K*g/kg) ], the derivative of
entropy with respect to Absolute Salinity and Conservative Temperature,
and eta_CT_CT [ (J/(K*kg))/K^2 ], the second derivative of
entropy with respect to Conservative Temperature.
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.
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_entropy_second_derivatives(SA, CT)
stopifnot(all.equal(r$eta_SA_SA, c(-0.007627718929669, -0.007591969960708, -0.007528186784540,
-0.007455177590576, -0.007441108287466, -0.007414368396280)))
stopifnot(all.equal(r$eta_SA_CT, c(-0.001833104216751, -0.001819473824306, -0.001580843823414,
-0.000930111408561, -0.000717011215195, -0.000548410546830)))
stopifnot(all.equal(r$eta_CT_CT, c(-0.043665023731109, -0.043781336189326, -0.045506114440888,
-0.049708939454018, -0.050938690879443, -0.051875017843472)))