gsw (version 1.0-5)

gsw_t_freezing_first_derivatives_poly: Derivatives of Freezing Water Properties (Polynomial version)

Description

Derivatives of Freezing Water Properties (Polynomial version)

Usage

gsw_t_freezing_first_derivatives_poly(SA, p, saturation_fraction = 1)

Arguments

SA

Absolute Salinity [ g/kg ]

p

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

saturation_fraction

fraction of air in water [unitless]

Value

a list containing tfreezing_SA [ K/(g/kg) ], the derivative of freezing temperature with Absolute Salinity and tfreezing_p [ K/dbar ], the derivative with respect to pressure.

Bugs

As of March 27, 2017, the test values listed in “Examples” do not match values provided at the TEOS-10 website listed in “References”, but they match with values given by the Matlab code that is provided on the TEOS-10 website. It is expected that the TEOS-10 website will be updated by May 2017. As those updates to the TEOS-10 website become available, the present comment will be revised or deleted.

Details

The present R function works with a wrapper to a C function contained within the GSW-C system (Version 3.05-4 dated 2017-08-07, available at https://github.com/TEOS-10/GSW-C, as git commit '5b4d959e54031f9e972f3e863f63e67fa4f5bfec'), which stems from the GSW-Fortran system (https://github.com/TEOS-10/GSW-Fortran) which in turn stems from the GSW-Matlab system (https://github.com/TEOS-10/GSW-Matlab). Consult http://www.teos-10.org to learn more about these software systems, their authorships, and the science behind it all.

References

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

See Also

Other functions with suspicious test values on the TEOS-10 website: gsw_entropy_second_derivatives, gsw_rho_second_derivatives_wrt_enthalpy, gsw_specvol_second_derivatives_wrt_enthalpy

Examples

# NOT RUN {
SA <- c(               34.7118, 34.8915, 35.0256, 34.8472, 34.7366, 34.7324)
p <- c(                     10,      50,     125,     250,     600,    1000)
saturation_fraction <- c(    1,     0.8,     0.6,     0.5,     0.4,       0)
derivs <- gsw_t_freezing_first_derivatives_poly(SA, p, saturation_fraction)
expect_equal(derivs$tfreezing_SA, c(-0.056810211094078, -0.056855567524973, -0.056901968693345,
                                  -0.056903498206432, -0.056975157476629, -0.057083526206200))
expect_equal(derivs$tfreezing_p/1e-7, c(-0.748987354878138, -0.750288853857513, -0.752676389629787,
                                      -0.756549680608529, -0.767482625710990, -0.779985619685683))
# }