swAlpha {oce} | R Documentation |
Compute alpha, the thermal expansion coefficient for seawater.
swAlpha(salinity, temperature=NULL, pressure=0, longitude=300, latitude=30, eos=getOption("oceEOS", default="gsw"))
salinity |
either practial salinity (in which case |
temperature |
in-situ temperature [degC], defined on
the ITS-90 scale; see “Temperature units” in the documentation for
|
pressure |
pressure [dbar] |
longitude |
longitude of observation (only used if |
latitude |
latitude of observation (only used if |
eos |
equation of state, either |
If the first argument is a ctd
object, then salinity,
temperature and pressure values are extracted from it, and used for the
calculation.
Value in 1/degC.
Dan Kelley
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.