Ratio of vert. gradient of pot. density to vert grad of locally-referenced pot density

Note that the C library had to be patched to get this working; a new version of the library will address the bug directly.

Usage

gsw_IPV_vs_fNsquared_ratio(SA, CT, p, p_ref = 0)

Arguments

SA: Absolute Salinity [ g/kg ]. The valid range for most `gsw` functions is 0 to 42 g/kg.
CT: Conservative Temperature [ degC ].
p: sea pressure [dbar], i.e. absolute pressure [dbar] minus 10.1325 dbar
p_ref: reference pressure [ dbar ]

Value

list containing IPV_vs_fNsquared_ratio [ unitless ] and mid-point pressure p_mid [ dbar ]

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.

References

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

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)
p <-  c(     10,      50,     125,     250,     600,    1000)
p_ref <- 0
r <- gsw_IPV_vs_fNsquared_ratio(SA, CT, p, p_ref)
stopifnot(all.equal(r$IPV_vs_fNsquared_ratio,
    c(0.999742244888022, 0.996939883468178, 0.986141997098021,
      0.931595598713477, 0.861224354872028)))
stopifnot(all.equal(r$p_mid, c(30, 87.5, 187.5, 425, 800)))