either practial salinity or an oce object; see
Details.
temperature
in-situ temperature [$^\circ$C], defined on
the ITS-90 scale; see Temperature units in the documentation for
swRho.
pressure
pressure [dbar].
referencePressure
reference pressure [dbar], e.g. 0 for
$\sigma_0$) calculation.
longitude
longitude of observation (only used if eos="gsw").
latitude
latitude of observation (only used if eos="gsw").
eos
name of equation of state to be used, either "unesco" or
"gsw".
Value
Potential density anomaly [kg/m$^3$], defined as
$\sigma_\theta=\rho(S,\theta(S,t,p),0$
- 1000 kg/m$^3$.
Details
If the first argument is an oce object, then salinity, etc.,
are extracted from it, and used for the calculation instead of any values
provided in the other arguments.
References
See citations provided in the swRho documentation.