swThermalConductivity {oce} | R Documentation |
Compute seawater thermal conductivity, in W/(m*degC)
swThermalConductivity(salinity, temperature=NULL, pressure=NULL)
salinity |
salinity [PSU], or a |
temperature |
in-situ temperature [degC], defined
on the ITS-90 scale; see “Temperature units” in the documentation for
|
pressure |
pressure [dbar] |
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”.)
If the first argument is an appropriate oce
object, then the salinity,
temperature and pressure values are extracted from it and then used in the
calculation, ignoring the values of the other arguments.
Conductivity of seawater in W/(m*degC).
To calculate thermal diffusivity in m^2/s, divide by the product of density and specific heat, as in the example.
Dan Kelley
Caldwell, Douglas R., 1974. Thermal conductivity of seawater, Deep-sea Research, 21, 131-137.
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 swThermalConductivity(0, 20, 0) / (swRho(0, 20, 0) * swSpecificHeat(0, 20, 0)) # lab # 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