oce (version 1.2-0)

swSigmaT: Seawater quasi-potential density anomaly

Description

Compute \(\sigma_t\), a rough estimate of potential density of seawater, minus 1000 kg/m\(^3\).

Usage

swSigmaT(
  salinity,
  temperature = NULL,
  pressure = NULL,
  longitude = NULL,
  latitude = NULL,
  eos = getOption("oceEOS", default = "gsw")
)

Arguments

salinity

either practical salinity (in which case temperature and pressure must be provided) or an oce object, in which case salinity, temperature (in the ITS-90 scale; see next item), etc. are inferred from the object.

temperature

in-situ temperature (\(^\circ\)C), defined on the ITS-90 scale. This scale is used by GSW-style calculation (as requested by setting eos="gsw"), and is the value contained within ctd objects (and probably most other objects created with data acquired in the past decade or two). Since the UNESCO-style calculation is based on IPTS-68, the temperature is converted within the present function, using T68fromT90().

pressure

pressure (dbar)

longitude

longitude of observation (only used if eos="gsw"; see ‘Details’).

latitude

latitude of observation (only used if eos="gsw"; see ‘Details’).

eos

equation of state, either "unesco" (references 1 and 2) or "gsw" (references 3 and 4).

Value

Quasi-potential density anomaly (kg/m\(^3\)), defined as the density calculated with pressure set to zero.

Details

If the first argument is an '>oce object, then salinity, etc., are extracted from it, and used for the calculation.

References

See citations provided in the swRho() documentation.

See Also

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(), swSigma(), swSoundAbsorption(), swSoundSpeed(), swSpecificHeat(), swSpice(), swTFreeze(), swTSrho(), swThermalConductivity(), swTheta(), swViscosity(), swZ()

Examples

# NOT RUN {
swSigmaT(35, 13, 1000, longitude=300, latitude=30, eos="gsw") # 26.39623
swSigmaT(35, T90fromT68(13), 1000, eos="unesco") # 26.39354

# }