Fossil turbulence revisited

A theory of fossil turbulence presented in the 11th Liege Colloquium on Marine Turbulence is ‘revisited’ in the 29th Liege Colloquium ‘Marine Turbulence Revisited’. The Gibson [Gibson, C.H., 1980. Fossil temperature, salinity, and vorticity turbulence in the ocean. : Nihoul, J. (Ed.), Marine Turbulence. Elsevier, Amsterdam, pp. 221–257] theory applied universal similarity theories of turbulence and turbulent mixing to the vertical evolution of an isolated patch of turbulence in a stratified fluid as it is constrained and fossilized by buoyancy forces. Towed oceanic microstructure measurements of Schedvin (1979) confirmed the predicted universal constants. Universal constants, spectra, hydrodynamic phase diagrams (HPDs) and other predictions of the theory have been reconfirmed by a wide variety of field and laboratory observations. AT (turbulent activity coefficient) vs. C (Cox number) HPDs classify microstructure patches as active, active-fossil, and fossil turbulence. So do Froude–Reynolds number Fr/Fro vs. Re/ReF plots. Both HPDs show most oceanic microstructure patches are fossilized. The oceanic microstructure community has not yet adopted the fossil turbulence paradigm, for reasons that include a variety of misconceptions about stratified turbulence and turbulent mixing. Confusion of fossilized microstructure with turbulent microstructure leads to vast underestimates of average dissipation rates of kinetic energy and scalar variance χ, and therefore vast underestimates of vertical fluxes in most ocean layers. Fossil turbulence theory has many applications; for example, in marine biology, laboratory and field measurements suggest phytoplankton species with different swimming abilities adjust their growth strategies differently by pattern recognition of several days of turbulence–fossil–turbulence dissipation and persistence times above threshold values, signaling a developing surface layer sea change. In cosmology, self-gravitational structure masses are interpreted as fossils of primordial hydrodynamic states.