Spiciness theory revisited, with new views on neutral density, orthogonality and passiveness

Content Provider	Scilit
Author	Tailleux, Rémi
Copyright Year	2020
Description	This paper clarifies the theoretical basis for constructing spiciness variables optimal for characterising ocean water masses. Three essential ingredients are identified: 1) a material density variable γ that is as neutral as feasible; 2) a material state function ξ independent of γ, but otherwise arbitrary; 3) an empirically determined function ξr(γ) of γ quantifying the isopycnal mean behaviour of ξ. The key results are: It is the anomaly ξ′ = ξ − ξr(γ), rather than ξ, that is the variable optimally suited for characterising ocean water masses; Ingredient 1) is required, because contrary to what is usually assumed, it is not the property of ξ that determine its dynamical inertness, but the degree of neutrality of γ; Oceanic sections of ξ′ are rather insensitive to the particular choice of ξ; Contrary to what has been usually assumed, it is orthogonality in physical space rather than in thermohaline space that is the relevant property for optimally characterising ocean water masses. The results are important because: They unify the various ways in which spiciness has been defined and used in the literature; They provide for the first time a rigorous first-principles physical justification for the concept of neutral density.
DOI	10.5194/os-2020-39
Language	English
Publisher	Copernicus GmbH
Publisher Date	2020-05-20
Access Restriction	Open
Subject Keyword	Marine Engineering Water Masses Ocean Water Optimally Characterising Ocean Optimal for Characterising
Content Type	Text
Resource Type	Article