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A new characterization of the turbulent diapycnal diffusivities of mass and momentum in the ocean
Author(s) -
Salehipour H.,
Peltier W. R.,
Whalen C. B.,
MacKin J. A.
Publication year - 2016
Publication title -
geophysical research letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.007
H-Index - 273
eISSN - 1944-8007
pISSN - 0094-8276
DOI - 10.1002/2016gl068184
Subject(s) - turbulence , momentum (technical analysis) , mixing (physics) , turbulent prandtl number , thermal diffusivity , prandtl number , mechanics , mass flux , environmental science , meteorology , atmospheric sciences , geology , climatology , physics , thermodynamics , reynolds number , convection , finance , quantum mechanics , nusselt number , economics
The diapycnal diffusivity of mass supported by turbulent events in the ocean interior plays a fundamental role in controlling the global overturning circulation. The conventional representation of this diffusivity, due to Osborn (1980), assumes a constant mixing efficiency. We replace this methodology by a generalized‐Osborn formula which involves a mixing efficiency that varies nonmonotonically with at least two nondimensional variables. Using these two variables, we propose dynamic parameterizations for mixing efficiency and turbulent Prandtl number (the latter quantifies the ratio of momentum to mass diapycnal diffusivities) based on the first synthesis of an extensive direct numerical simulation of inhomogeneously stratified shear‐induced turbulence. Data from Argo floats are employed to demonstrate the extent of the spatial and statistical variability to be expected in both the diapycnal diffusivities of mass and momentum. We therefore suggest that previous estimates of these important characteristics of the global ocean require reconsideration.