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Anisotropic Macroturbulence and Diffusion Associated with a Westward Zonal Jet: From Laboratory to Planetary Atmospheres and Oceans
Physical Review E
  • Boris Galperin, University of South Florida
  • Jesse Hoemann, University of South Florida
  • Stefania Espa, Sapienza Università di Roma
  • Gabriella Di Nitto, Sapienza Università di Roma
  • Guglielmo Lacorata, ISAC, National Research Council
Document Type
Article
Publication Date
1-1-2016
Digital Object Identifier (DOI)
https://doi.org/10.1103/PhysRevE.94.063102
Disciplines
Abstract

Turbulence with inverse energy cascade and its transport properties are investigated experimentally in a flow associated with a westward propagating jet. Turbulence and the jet were produced by an electromagnetic force in a rotating tank filled with an electrolytic saline solution. The parabolic free surface emulated the topographic β effect which evoked the zonation. The spectral and transport flow characteristics were highly anisotropic. Turbulence is diagnosed by exploring the analogy between vertical and horizontal turbulent overturns in, respectively, stably stratified and quasigeostrophic flows which gives rise to a method of potential vorticity (PV) monotonizing. The anisotropization of transport properties of the flow is investigated using the finite scale Lyapunov exponent technique. After initial exponential particle separation, radial (meridional in geophysical and planetary applications) diffusion attains a short-ranged Richardson regime which transitions to the Taylor (scale-independent diffusivity) one. The azimuthal (zonal) diffusion exhibits a double-plateau structure which attains a superdiffusive regime on large scales. The transition to the Taylor regime for the radial diffusion takes place at a scale of turbulence anisotropization. The radial eddy diffusivity in both regimes as well as the transition scale are all determined by the rate of the inverse energy cascade, ε, that can be diagnosed by the PV monotonizing. Conversely, ε can be deduced from the scale of the Richardson-Taylor regime transition in the radial eddy diffusivity which, thus, provides an additional tool of diagnosing anisotropic macroturbulence with inverse energy cascade.

Citation / Publisher Attribution

Physical Review E, v. 94, art. 063102

Citation Information
Boris Galperin, Jesse Hoemann, Stefania Espa, Gabriella Di Nitto, et al.. "Anisotropic Macroturbulence and Diffusion Associated with a Westward Zonal Jet: From Laboratory to Planetary Atmospheres and Oceans" Physical Review E Vol. 94 (2016)
Available at: http://works.bepress.com/boris-galperin/13/