swAlpha {oce}R Documentation

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 [degC], 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".

Details

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

Value

Value in 1/degC.

Author(s)

Dan Kelley

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.


[Package oce version 0.9-18 Index]