oce (version 0.9-18)

swSigma0: Seawater potential density anomaly reference to standardized pressures

Description

Compute $\sigma_\theta$, the potential density of seawater (minus 1000 kg/m$^3$), referenced to various pressures, i.e swSigma0 is referenced to the surface and is thus identical to swSigmaTheta, while swSigma1 is referenced to 1000dbar, swSigma2 is referenced to 2000dbar, swSigma2 is referenced to 3000dbar, and swSigma4 is referenced to 4000dbar.

Usage

swSigma0(salinity, temperature, pressure,
    longitude=300, latitude=30, eos=getOption("oceEOS", default="gsw"))
swSigma1(salinity, temperature, pressure,
    longitude=300, latitude=30, eos=getOption("oceEOS", default="gsw"))
swSigma2(salinity, temperature, pressure,
    longitude=300, latitude=30, eos=getOption("oceEOS", default="gsw"))
swSigma3(salinity, temperature, pressure,
    longitude=300, latitude=30, eos=getOption("oceEOS", default="gsw"))
swSigma4(salinity, temperature, pressure,
    longitude=300, latitude=30, eos=getOption("oceEOS", default="gsw"))

Arguments

salinity

either practial salinity (in which case temperature and pressure must be provided) or an oce object (in which case salinity, etc. are inferred from the object).

temperature

in-situ temperature [$^\circ$C], defined on the ITS-90 scale; see Temperature units in the documentation for swRho.

pressure

pressure [dbar]

longitude

longitude of observation (only used if eos="gsw").

latitude

latitude of observation (only used if eos="gsw").

eos

equation of state, either "unesco" [1,2] or "gsw".

Value

• Potential density anomaly [kg/m$^3$].

Details

If the first argument is a ctd object or section object, then salinity, etc., values are extracted from it, and used for the calculation.

Definition: $\sigma_0=\sigma_\theta=\rho(S,\theta(S,t,p),0$ - 1000 kg/m$^3$.

References

See citations provided in the swRho documentation.

See Also

Related density routines include: swSigmaTheta, which these functions employ, and also swRho, and (mostly for historical use) swSigmaT.

Examples

swSigmaTheta(35, 13, 1000)
swSigma0(35, 13, 1000)
swSigma1(35, 13, 1000)
swSigma2(35, 13, 1000)
swSigma3(35, 13, 1000)