The three-dimensional vortical nature of atmospheric and oceanic turbulent flows

David Gerard Dritschel, Manuel de la Torre Juarez, Maarten HP Ambaum

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46 Citations (Scopus)

Abstract

Using a novel numerical method at unprecedented resolution, we demonstrate that structures of small to intermediate scale in rotating, stratified flows are intrinsically three-dimensional. Such flows are characterized by vortices (spinning volumes of fluid), regions of large vorticity gradients, and filamentary structures at all scales. It is found that such structures have predominantly three-dimensional dynamics below a horizontal scale L approximate to 1/2 L-R, where L-R is the so-called Rossby radius of deformation, equal to the characteristic vertical scale of the fluid H divided by the ratio of the rotational and buoyancy frequencies f/N. The breakdown of two-dimensional dynamics at these scales is attributed to the so-called "tall-column instability" [D. G. Dritschel and M. de la Torre Juarez, J. Fluid, Mech. 328, 129 (1996)], which is active on columnar vortices that are tall after scaling by f/N, or, equivalently, that are narrow compared with L-R. Moreover, this instability eventually leads to a simple relationship between typical vertical and horizontal scales: for each vertical wave number (apart from the vertically averaged, barotropic component of the flow) the average horizontal wave number is equal to f/N times the vertical wave number. The practical implication is that three-dimensional modeling is essential to capture the behavior of rotating, stratified fluids, Two-dimensional models are not valid fur scales below L-R. (C) 1999 American Institute of Physics. [S1070-6631(99)02405-8].

Original languageEnglish
Pages (from-to)1512-1520
Number of pages9
JournalPhysics of Fluids
Volume11
Issue number6
DOIs
Publication statusPublished - Jun 1999

Keywords

  • 2-DIMENSIONAL VORTEX INTERACTIONS
  • QUASI-GEOSTROPHIC TURBULENCE
  • CONTOUR DYNAMICS
  • FLUID
  • STRATOSPHERE
  • INSTABILITY
  • EQUATIONS
  • MOTION

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