R: Geostrophic Dynamic Height Anomaly

gsw_geo_strf_dyn_height {gsw} | R Documentation

## 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 9.7963m/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

### 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.

### Value

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

### 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

    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))

[Package gsw version 1.0-5 Index]