Compute electrical conductivity ratio based on salinity, temperature, and pressure (relative to the conductivity of seawater with salinity=35, temperature68=15, and pressure=0).

swCSTp(
salinity,
temperature = 15,
pressure = 0,
eos = getOption("oceEOS", default = "gsw")
)

## Arguments

salinity

practical salinity, or a CTD object (in which case its temperature and pressure are used, and the next two arguments are ignored)

temperature

in-situ temperature ($$^\circ$$C), defined on the ITS-90 scale; see the examples, as well as the “Temperature units” section in the documentation for swRho().

pressure

pressure (dbar)

eos

equation of state, either "unesco" or "gsw".

## Value

Conductivity ratio (unitless), i.e. the ratio of conductivity to the conductivity at salinity=35, temperature=15 (IPTS-68 scale) and pressure=0, which has numerical value 42.9140 mS/cm = 4.29140 S/m (see Culkin and Smith, 1980, in the regression result cited at the bottom of the left-hand column on page 23).

## Details

If eos="unesco", the calculation is done by a bisection root search on the UNESCO formula relating salinity to conductivity, temperature, and pressure (see swSCTp()). If it is "gsw" then the Gibbs-SeaWater formulation is used, via gsw_C_from_SP().

For thermal (as opposed to electrical) conductivity, see swThermalConductivity(). For computation of salinity from electrical conductivity, see swSCTp().

Other functions that calculate seawater properties: T68fromT90(), T90fromT48(), T90fromT68(), computableWaterProperties(), locationForGsw(), swAbsoluteSalinity(), swAlphaOverBeta(), swAlpha(), swBeta(), 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(), swTheta(), swViscosity(), swZ()

Dan Kelley

## Examples

stopifnot(abs(1.0 - swCSTp(35, T90fromT68(15), 0, eos="unesco")) < 1e-7)
stopifnot(abs(1.0 - swCSTp(34.25045, T90fromT68(15), 2000, eos="unesco")) < 1e-7)
stopifnot(abs(1.0 - swCSTp(34.25045, T90fromT68(15), 2000, eos="gsw")) < 1e-7)