| swTheta {oce} | R Documentation |
Seawater Potential Temperature (UNESCO Version)
Description
Compute the potential temperature of seawater, denoted \theta
in the UNESCO system, and pt in the GSW system.
Usage
swTheta(
salinity,
temperature = NULL,
pressure = NULL,
referencePressure = 0,
longitude = NULL,
latitude = NULL,
eos = getOption("oceEOS", default = "gsw")
)
Arguments
salinity |
either salinity (PSU) (in which case |
temperature |
in-situ temperature ( |
pressure |
pressure (dbar) |
referencePressure |
reference pressure (dbar) |
longitude |
longitude of observation (only used if |
latitude |
latitude of observation (only used if |
eos |
equation of state, either |
Details
Different formulae are used depending on the equation of state. If eos
is "unesco", the method of Fofonoff et al. (1983) is used
(see references 1 and 2).
Otherwise, swTheta uses gsw::gsw_pt_from_t() from
the gsw package.
If the first argument is a ctd or section 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.
Value
Potential temperature (^\circC) of seawater, referenced
to pressure referencePressure.
Author(s)
Dan Kelley
References
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
Gill, A.E., 1982. Atmosphere-ocean Dynamics, Academic Press, New York, 662 pp.
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.
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
Other functions that calculate seawater properties:
T68fromT90(),
T90fromT48(),
T90fromT68(),
computableWaterProperties(),
locationForGsw(),
swAbsoluteSalinity(),
swAlphaOverBeta(),
swAlpha(),
swBeta(),
swCSTp(),
swConservativeTemperature(),
swDepth(),
swDynamicHeight(),
swLapseRate(),
swN2(),
swPressure(),
swRho(),
swRrho(),
swSCTp(),
swSR(),
swSTrho(),
swSigma0(),
swSigma1(),
swSigma2(),
swSigma3(),
swSigma4(),
swSigmaTheta(),
swSigmaT(),
swSigma(),
swSoundAbsorption(),
swSoundSpeed(),
swSpecificHeat(),
swSpice(),
swSstar(),
swTFreeze(),
swTSrho(),
swThermalConductivity(),
swViscosity(),
swZ()
Examples
library(oce)
# Example 1: test value from Fofonoff et al., 1983
stopifnot(abs(36.8818748026 - swTheta(40, T90fromT68(40), 10000, 0, eos = "unesco")) < 0.0000000001)
# Example 2: a deep-water station. Note that theta and CT are
# visually identical on this scale.
data(section)
stn <- section[["station", 70]]
plotProfile(stn, "temperature", ylim = c(6000, 1000))
lines(stn[["theta"]], stn[["pressure"]], col = 2)
lines(stn[["CT"]], stn[["pressure"]], col = 4, lty = 2)
legend("bottomright",
lwd = 1, col = c(1, 2, 4), lty = c(1, 1, 2),
legend = c("in-situ", "theta", "CT"),
title = sprintf("MAD(theta-CT)=%.4f", mean(abs(stn[["theta"]] - stn[["CT"]])))
)