| Volumes and Issues Contents of Issue 1 Special Issue |
www.nonlin-processes-geophys.net/13/83/2006/
doi:10.5194/npg-13-83-2006
© Author(s) 2006. This work is licensed
under a Creative Commons License.
Anisotropic turbulence and zonal jets in rotating flows with a β-effect
1College of Marine Science, University of South Florida, St. Petersburg, FL 33701, USA
2Department of Mechanical Engineering/Perlstone Center for Aeronautical Engineering Studies, Ben-Gurion University of the Negev, Beer-Sheva 84105, Israel
3Atmospheric, Oceanic & Planetary Physics, Department of Physics, Clarendon Laboratory, Parks Road, Oxford, OX1 3PU, UK
Abstract. Numerical studies of small-scale forced, two-dimensional turbulent flows on the surface of a rotating sphere have revealed strong large-scale anisotropization that culminates in the emergence of quasi-steady sets of alternating zonal jets, or zonation. The kinetic energy spectrum of such flows also becomes strongly anisotropic. For the zonal modes, a steep spectral distribution, E(n)=CZ (Ω/R)2 n-5, is established, where CZ=O(1) is a non-dimensional coefficient, Ω is the angular velocity, and R is the radius of the sphere, respectively. For other, non-zonal modes, the classical, Kolmogorov-Batchelor-Kraichnan,
spectral law is preserved.
This flow regime, referred to as a zonostrophic regime, appears to have wide applicability to large-scale planetary and terrestrial
circulations as long as those are characterized by strong rotation, vertically stable stratification and small Burger numbers.
The well-known manifestations of this regime are the banded disks of the outer planets of our Solar System. Relatively less
known examples are systems of narrow, subsurface, alternating zonal jets throughout all major oceans discovered in
state-of-the-art, eddy-permitting simulations of the general oceanic circulation. Furthermore, laboratory experiments recently
conducted using the Coriolis turntable have basically confirmed that the lateral gradient of ''planetary vorticity'' (emulated via
the topographic β-effect) is the primary cause of the zonation and that the latter is entwined with the development of the
strongly anisotropic kinetic energy spectrum that tends to attain the same zonal and non-zonal distributions,
−5 and , respectively, in
both the slope and the magnitude, as the corresponding spectra in other environmental conditions. The non-dimensional
coefficient CZ in the −5 spectral law appears to be invariant,
, in a variety of simulated and natural flows.
This paper provides a brief review of the zonostrophic regime. The review includes the discussion of the physical nature, basic mechanisms, scaling laws and universality of this regime. A parameter range conducive to its establishment is identified, and collation of laboratory and naturally occurring flows is presented through which the zonostrophic regime manifests itself in the real world.
Full Article (PDF, 2158 KB) Special Issue
Citation: Galperin, B., Sukoriansky, S., Dikovskaya, N., Read, P. L., Yamazaki, Y. H., and Wordsworth, R.: Anisotropic turbulence and zonal jets in rotating flows with a β-effect, Nonlin. Processes Geophys., 13, 83-98, doi:10.5194/npg-13-83-2006, 2006. Bibtex EndNote Reference Manager XML
