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By definition, flows are not turbulent at scales where buoyancy forces or viscous forces dominate. Hydrodynamic phase diagrams (HPDs) are used to classify oceanic microstructure patches according to their hydrodynamic states. There are four possibilities, represented by the quadrants of the HPD shown in the slide: "active turbulence", "active-fossil", "fossil", and "non-turbulent" corresponding to the normalized Froude number/normalized Reynolds number position of the patch on the plot. Fr/Fr_o = (eps/eps_o)^1/3 where eps is the viscous dissipation rate in the patch and eps_o is the dissipation rate at the beginning of fossilization inferred from the maximum Thorpe overturn scale (the vertical patch size) L_T and the ambient stratification frequency N using eps_o = 3 L_T ^2 N^3. The normalized Reynolds number Re/Re_F = eps/eps_F is found using eps_F = 30 \nu N^2 from the Gibson 1980 theory. As shown, dominant patches of turbulence in the ocean are so rare that only their fossils (active-fossils) have been detected in most layers.
astro-ph/9904237, astro-ph/9904330

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