gsw (version 1.0-5)

gsw_geo_strf_dyn_height: Geostrophic Dynamic Height Anomaly

Description

This calculates a geopotential anomaly, called either the dynamic height anomaly or the geostrophic streamfunction in the TEOS-10 document listed as [1] below; users should read that and the references therein for more details on the definition and its calculation here.

To get the column-integrated value in meters, take the first value of the returned vector and divide by 9.7963\(m/s^2\). Note that this yields an integral with the top measured pressure (not zero) as an upper limit.

Usage

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

Arguments

SA

Absolute Salinity [ g/kg ]

CT

Conservative Temperature [ degC ]

p

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

p_ref

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

Value

A vector containing geopotential anomaly in \(m^2/s^2\) for each level. For more on the units, see [2].

Details

Because of the scheme used in the underlying C code, the pressures must be in order, and must not have any repeats. Also, there must be at least 4 pressure values. Violating any of these three restrictions yields an error.

If p_ref exceeds the largest p value, a vector of zeros is returned, in accordance with the underlying C code.

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

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

2. Talley et al., 2011. Descriptive Physical Oceanography, 6th edition, Elsevier.

Examples

# NOT RUN {
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 <- 1000
dh <- gsw_geo_strf_dyn_height(SA, CT, p, p_ref)
expect_equal(dh, c(17.039204557769487, 14.665853784722286, 10.912861136923812,
                 7.567928838774945, 3.393524055565328, 0))
# }