R: Seawater potential density anomaly referenced to 4000db...

swSigma4 {oce}

R Documentation

Seawater potential density anomaly referenced to 4000db pressure

Compute sigma, the potential density of seawater (minus 1000 kg/m^3), referenced to 4000db pressures.

swSigma4(salinity, temperature = NULL, pressure = NULL,
  longitude = NULL, latitude = NULL, eos = getOption("oceEOS",
  default = "gsw"))

`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 [degC], 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"` [1,2] or `"gsw"` [3,4].

Definition: sigma_1=sigma_theta=rho(S,theta(S,t,p),4000) - 1000 kg/m^3.

Potential density anomaly [kg/m^3].

Dan Kelley

See citations provided in the swRho documentation.

[Package oce version 1.0-1 Index]