gsw_SAAR {gsw} | R Documentation |
Absolute Salinity Anomaly Ratio
gsw_SAAR(p, longitude, latitude)
p |
sea pressure [dbar], i.e. absolute pressure [dbar] minus 10.1325 dbar |
longitude |
longitude in decimal degrees, positive to the east of Greenwich. (This
is called |
latitude |
latitude in decimal degrees, positive to the north of the equator. (This
is called |
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.
a list containing SAAR
, which is
the (unitless) Absolute Salinity Anomality Ratio, and in_ocean
is set to 1 if SAAR
is nonzero, or to 0 otherwise.
The definition of in_ocean
is incorrect, because the C function named
gsw_saar
, which is called by the present R function, does not calculate
in_ocean
, as the base Matlab function named gsw_SAAR
does. However,
examination of the Matlab code shows that in_ocean
is set to 0 along
with SAAR
, whenever the original estimate of the latter is nonfinite.
Thus, points that would be siganlled as being on the land by the Matlab code
are indicated in the same way with the present R function. However, other points
may also be indicated as being on land, if SAAR
is simply zero in the
first calculation. Whether this poses a problem in practice is an open question,
since it seems likely that this function would only be called with oceanic
locations, anyway. If problems arise for users, a patch can be written to
improve things.
http://www.teos-10.org/pubs/gsw/html/gsw_saar.html
p <- c(10, 50, 125, 250, 600, 1000) longitude <- c(188, 188, 188, 188, 188, 188) latitude <- c(4, 4, 4, 4, 4, 4) SAAR <- gsw_SAAR(p, longitude, latitude) expect_equal(1e3*SAAR$SAAR, c(0.004794295602143, 0.007668755837570, 0.018919828449091, 0.077293264028981, 0.161974583039298, 0.270652408428964)) expect_equal(SAAR$in_ocean, rep(1, 6))