Quantifying Climate Signals: Spicity, Orthogonality, and Distance

The variability of water masses has been analyzed using temperature and salinity or density and various forms of spicity/spiciness. The objective way of comparing these spicity/spiciness functions is not the difference between these definitions; instead, it is through the application of these functions in tracing water masses and climate signal analysis. The major advantage of the spicity function introduced by Huang et al. Journal of Geophysical Research: Oceans , is that this function in combination with density gives rise to an orthogonal coordinate, in which the signals are separated into two independent components. In addition, a new quantity, distance, is introduced, that can be used to trace water masses both along and across isopycnal surfaces. Spicity can serve as an appropriate tool to extract globally varying water mass properties as a supplement to variations of density alone.