Compute seawater "spice" (a variable orthogonal to density in TS space).
swSpice(salinity, temperature = NULL, pressure = NULL)either salinity [PSU] (in which case temperature and
pressure must be provided) or a ctd object (in which
case salinity, temperature and 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
swRho.
seawater pressure [dbar]
Spice [kg/m\(^3\)].
If the first argument is a ctd object, then salinity, temperature and
pressure values are extracted from it, and used for the calculation.
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). The definition used here is that of Pierre Flament. (Other formulations exist.) Note that pressure is ignored in the definition. Spiciness is sometimes denoted \(\pi(S,t,p)\).
P. Flament, 2002. A state variable for characterizing water masses and their diffusive stability: spiciness. Progr. Oceanog., 54, 493-501.
Other functions that calculate seawater properties: T68fromT90,
T90fromT48, T90fromT68,
swAbsoluteSalinity,
swAlphaOverBeta, swAlpha,
swBeta, swCSTp,
swConservativeTemperature,
swDepth, swDynamicHeight,
swLapseRate, swN2,
swPressure, swRho,
swRrho, swSCTp,
swSTrho, swSigma0,
swSigma1, swSigma2,
swSigma3, swSigma4,
swSigmaTheta, swSigmaT,
swSigma, swSoundAbsorption,
swSoundSpeed, swSpecificHeat,
swTFreeze, swTSrho,
swThermalConductivity,
swTheta, swViscosity,
swZ