Compute seawater "spice", also called "spiciness" (a variable orthogonal
to density in TS space), in either of two formulations, depending on
the value of the
eos argument. If
Flament's (reference 1) formulation is used. If
then the Gibbs SeaWater formulation for "spiciness0" is used
(see reference 2).
swSpice( salinity, temperature = NULL, pressure = NULL, longitude = NULL, latitude = NULL, eos = getOption("oceEOS", default = "gsw") )
either salinity (PSU) (in which case
pressure must be provided) or a
ctd object (in which
pressure are determined
from the object, and must not be provided in the argument list).
in-situ temperature (\(^\circ\)C) on the
ITS-90 scale; see “Temperature units” in the documentation for
Seawater pressure (dbar) (only used if
"gsw"); see “Details”..
longitude of observation (only used if
"gsw"; see “Details”).
latitude of observation (only used if
"gsw"; see “Details”).
Character value specifying the equation of state,
"unesco" (for the Flament formulation, although this
is not actually part of UNESCO)
"gsw" for the Gibbs SeaWater formulation.
Flament-formulated spice \(kg/m^3\) if
or surface-referenced GSW spiciness0 \(kg/m^3\) if
the latter provided by
gsw::gsw_spiciness0(), and hence aimed
at application within the top half-kilometre of the ocean.
If the first argument is a
ctd object, then salinity, temperature and
pressure values are extracted from it, and used for the calculation. (For
eos="gsw" case, longitude and latitude are also extracted, because
these are required for the formulation of spiciness0.
Roughly speaking, seawater with a high spiciness is relatively warm and salty compared with less spicy water. Another interpretation is that spice is a variable measuring distance orthogonal to isopycnal lines on TS diagrams (if the diagrams are scaled to make the isopycnals run at 45 degrees). Note that pressure, longitude and latitude are all ignored in the Flament definition.
Flament, P. “A State Variable for Characterizing Water Masses and Their Diffusive Stability: Spiciness.” Progress in Oceanography, Observations of the 1997-98 El Nino along the West Coast of North America, 54, no. 1 (July 1, 2002):493-501. doi:10.1016/S0079-6611(02)00065-4
2.McDougall, Trevor J., and Oliver A. Krzysik. “Spiciness.”
Journal of Marine Research 73, no. 5 (September 1, 2015): 141-52.
Other functions that calculate seawater properties: