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oce (version 0.9-18)

swAlpha: Seawater thermal expansion coefficient

Description

Compute $\alpha$, the thermal expansion coefficient for seawater.

Usage

swAlpha(salinity, temperature=NULL, pressure=0,
       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"; see Details).
latitude
latitude of observation (only used if eos="gsw"; see Details).
eos
equation of state, either "unesco" or "gsw".

Value

  • Value in 1/degC.

Details

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

References

The eos="unesco" formulae are based on the UNESCO equation of state, but are formulated empirically by Trevor J. McDougall, 1987, Neutral Surfaces, Journal of Physical Oceanography, volume 17, pages 1950-1964. The eos="gsw" formulae come from GSW; see references in the swRho documentation.