# swThermalConductivity: Seawater thermal conductivity In oce: Analysis of Oceanographic Data

## Description

Compute seawater thermal conductivity, in W/(m*degC)

## Usage

 `1` ```swThermalConductivity(salinity, temperature = NULL, pressure = NULL) ```

## Arguments

 `salinity` salinity [PSU], or a `ctd` object, in which case `temperature` and `pressure` will be ignored. `temperature` in-situ temperature [degC], defined on the ITS-90 scale; see “Temperature units” in the documentation for `swRho`. `pressure` pressure [dbar]

## 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”.)

## Value

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

## References

Caldwell, Douglas R., 1974. Thermal conductivity of seawater, Deep-sea Research, 21, 131-137.

Other functions that calculate seawater properties: `T68fromT90`, `T90fromT48`, `T90fromT68`, `swAbsoluteSalinity`, `swAlphaOverBeta`, `swAlpha`, `swBeta`, `swCSTp`, `swConservativeTemperature`, `swDepth`, `swDynamicHeight`, `swLapseRate`, `swN2`, `swPressure`, `swRho`, `swRrho`, `swSCTp`, `swSTrho`, `swSigma0`, `swSigma1`, `swSigma2`, `swSigma3`, `swSigma4`, `swSigmaTheta`, `swSigmaT`, `swSigma`, `swSoundAbsorption`, `swSoundSpeed`, `swSpecificHeat`, `swSpice`, `swTFreeze`, `swTSrho`, `swTheta`, `swViscosity`, `swZ`
 ```1 2 3 4 5 6 7 8``` ```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 ```