Compute seawater thermal conductivity, in \(W m^{-1\circ}C^{-1}\)
Arguments
- salinity
salinity (PSU), or a
ctdobject, in which casetemperatureandpressurewill be ignored.- temperature
in-situ temperature (\(^\circ\)C), defined on the ITS-90 scale; see “Temperature units” in the documentation for
swRho().- pressure
pressure (dbar)
Value
Conductivity of seawater in \(W m^{-1} {^\circ} C^{-1}\). To calculate thermal diffusivity in \(m^2/s^2\), divide by the product of density and specific heat, as in the example.
Details
Caldwell's (1974) detailed formulation is used. To be specific, his equation 6 to calculate K, and his two sentences above that equation are used to infer this to be K(0,T,S) in his notation of equation 7. Then, application of his equations 7 and 8 is straightforward. He states an accuracy for this method of 0.3 percent. (See the check against his Table 1 in the “Examples”.)
References
Caldwell, Douglas R., 1974. Thermal conductivity of seawater, Deep-sea Research, 21, 131-137.
See also
Other functions that calculate seawater properties:
T68fromT90(),
T90fromT48(),
T90fromT68(),
computableWaterProperties(),
locationForGsw(),
swAbsoluteSalinity(),
swAlpha(),
swAlphaOverBeta(),
swBeta(),
swCSTp(),
swConservativeTemperature(),
swDepth(),
swDynamicHeight(),
swLapseRate(),
swN2(),
swPressure(),
swRho(),
swRrho(),
swSCTp(),
swSR(),
swSTrho(),
swSigma(),
swSigma0(),
swSigma1(),
swSigma2(),
swSigma3(),
swSigma4(),
swSigmaT(),
swSigmaTheta(),
swSoundAbsorption(),
swSoundSpeed(),
swSpecificHeat(),
swSpice(),
swSpiciness0(),
swSpiciness1(),
swSpiciness2(),
swSstar(),
swTFreeze(),
swTSrho(),
swTheta(),
swViscosity(),
swZ()
Examples
library(oce)
# Values in m^2/s, a unit that is often used instead of W/(m*degC).
swThermalConductivity(35, 10, 100) / (swRho(35, 10, 100) * swSpecificHeat(35, 10, 100)) # ocean
#> [1] 1.512538e-07
swThermalConductivity(0, 20, 0) / (swRho(0, 20, 0) * swSpecificHeat(0, 20, 0)) # lab
#> [1] 1.526025e-07
# Caldwell Table 1 gives 1478e-6 cal/(cm*sec*degC) at 31.5 o/oo, 10degC, 1kbar
joulePerCalorie <- 4.18400
cmPerM <- 100
swThermalConductivity(31.5, 10, 1000) / joulePerCalorie / cmPerM
#> [1] 0.00147754