Session DJ - Geophysical Fluid Dynamics I.
ORAL session, Sunday afternoon, November 24
Metropolitan Ballroom, Wyndham Anatole Hotel
We have conducted experiments and numerical simulations on turbulence in a rapidly rotating annulus. Eddies produced by our small scale forcing, which has zero net vorticity, are found to evolve into an azimuthal flow with three zones(J. Aubert, S. Jung and H.L. Swinney, Geophys. Res. Lett., to appear). These jets have high Reynolds number (6000 \sim 14000) and low Rossby number (0.05 \sim 0.1) indicating a turbulent quasi-2D flow. Systems with long range correlations, such as this flow with its large vortices and jets, are described by nonextensive rather than extensive thermodynamics, i.e., the entropy of a system comprised of two subsystems is not given by the sum of the entropies of the subsystems. We explore the applicability of a nonextensive statistical mechanics formalism proposed by Tsallis(C. Tsallis, J. Stat. Phys. 52, 479 (1988)) to this problem. Assuming energy and enstrophy conservation in an inviscid fluid, we deduce the radial dependence of the mean vorticity and the probability density function of vorticity that are in good agreement with the observations.