Geophysical and Astrophysical Fluid Dynamics

Abstract:

The banded patterns of cloud and wind are among the most striking features of the atmospheres of Jupiter and Saturn, but their dynamical origin remains poorly understood. Most approaches towards understanding zonation so far (also in the terrestrial oceans) have used highly idealized models to show that it might originate from dynamical anisotropy in a shallow turbulent fluid layer due to the planetary β-effect. Here we report the results of laboratory experiments, conducted on a 14-m diameter turntable, which quantitatively confirm that multiple zonal jets may indeed be generated and maintained by this mechanism in the presence of deep convection and a topographic β-effect. At the very small values of Ekman number (≤2 × 10-5) and large local Reynolds numbers (≥2000, based onjet scales) achieved, the kinetic energy spectra suggest the presence of both energy-cascading and enstrophy-cascading inertial ranges in addition to the zonation near twice the Rhines wave number. Copyright 2004 by the American Geophysical Union.

Abstract:

Banded structure: belts and zones, changes in zonal velocity, evidence of upwelling and downwelling; Dicrete features: great red spot, white ovals and other anticyclones, cyclonic features, eddy momentum flux; Temperatures and vertical structure: global temperature variations, thermal waves, vertical structure - winds, temperature; Moist convection and lightning: lightning distribution, convective heat flux and structure of the lightning clouds, energy of lightning flashes, depth of lightning, models of moist convection; Models of the zonal jets: banding controlled in the weather layer, deep winds and stability of the jets, banding controlled in the interior, modes of internal heat transfer, banding controlled by tides, equatorial superrotation; Models of discrete features: stabel vortices, statistical mechanics models, equatorial hot spots and the Galileo probe; Unanswered questions and possible solutions.