oce (version 0.9-18)

swRho: Seawater density

Description

Compute $\rho$, the in-situ density of seawater.

Usage

swRho(salinity, temperature=NULL, pressure=NULL,
    longitude, latitude, eos=getOption("oceEOS", default="gsw"))

Arguments

salinity

either practical salinity (in which case temperature and pressure must be provided) or an oce object, in which case salinity, temperature (in the ITS-90 scale; see

temperature

in-situ temperature [$^\circ$C], defined on the ITS-90 scale. This scale is used by GSW-style calculation (as requested by setting eos="gsw"), and is the value contained within ctd objects (and probably most

pressure

pressure [dbar]

longitude

longitude of observation (only used if eos="gsw"; see Details).

latitude

latitude of observation (only used if eos="gsw"; see Details).

eos

equation of state, either "unesco" [1,2] or "gsw" [3,4].

Value

• In-situ density [kg/m$^3$].

Temperature units

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.

Details

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.

References

[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.

See Also

Related density routines include swSigma0 (and equivalents at other pressure horizons), swSigmaT, and swSigmaTheta.

Examples

library(oce)
rho <- swRho(35, 13, 1000)