swRho {oce} | R Documentation |
Compute rho, the in-situ density of seawater.
swRho(salinity, temperature=NULL, pressure=NULL, longitude, latitude, eos=getOption("oceEOS", default="gsw"))
salinity |
either practical salinity (in which case |
temperature |
in-situ temperature [degC], defined
on the ITS-90 scale. This scale is used by GSW-style calculation (as
requested by setting |
pressure |
pressure [dbar] |
longitude |
longitude of observation (only used if |
latitude |
latitude of observation (only used if |
eos |
equation of state, either |
If the first argument is an oce
object, then values for
salinity, etc., are extracted from it, and used for the calculation, and the
corresponding arguments to the present function are ignored.
If eos="unesco"
, the density is calculated using the UNESCO equation of
state for seawater [1,2], and if eos="gsw"
, the GSW formulation [3,4]
is used.
In-situ density [kg/m^3].
The UNESCO formulae are defined in terms of
temperature measured on the IPTS-68 scale, whereas the replacement GSW
formulae are based on the ITS-90 scale. Prior to the addition of GSW
capabilities, the various sw*
functions took temperature to be in
IPTS-68 units. As GSW capabilities were added in early 2015, the assumed unit
of temperature
was taken to be ITS-90. This change means that old code
has to be modified, by replacing e.g. swRho(S, T, p)
with
swRho(S, T90fromT68(T), p)
. At typical oceanic values, the difference
between the two scales is a few millidegrees.
Dan Kelley
[1] Fofonoff, P. and R. C. Millard Jr, 1983. Algorithms for computation of fundamental properties of seawater. Unesco Technical Papers in Marine Science, 44, 53 pp
[2] Gill, A.E., 1982. Atmosphere-ocean Dynamics, Academic Press, New York, 662 pp.
[3] IOC, SCOR, and IAPSO (2010). The international thermodynamic equation of seawater-2010: Calculation and use of thermodynamic properties. Technical Report 56, Intergovernmental Oceanographic Commission, Manuals and Guide.
[4] McDougall, T.J. and P.M. Barker, 2011: Getting started with TEOS-10 and the Gibbs Seawater (GSW) Oceanographic Toolbox, 28pp., SCOR/IAPSO WG127, ISBN 978-0-646-55621-5.
Related density routines include
swSigma0
(and equivalents at other pressure horizons),
swSigmaT
, and
swSigmaTheta
.
library(oce) rho <- swRho(35, 13, 1000)