BANDED CONVECTION IN ROTATING FLUID SPHERES AND THE CIRCULATION OF THE JOVIAN ATMOSPHERE

Laboratory experiments of thermal convection in rotating spherical she lls exhibit symmetric bands and alternating zonal jets in a thin layer near the outer boundary at high rotation rates and at Rayleigh number s far in excess of the critical value. The bands result from large-sca le ordering of small-scale columnar convection deeper in the shell and the zonal jets are secondary flows derived from the columnar convecti on. The number of bands and the strength of the zonal jets increase wi th increasing rotation rate and with increasing Rayleigh number of the convection. The bands are best defined in the fluid outside of the cy linder tangent to the inner spherical boundary. In a spherical shell w ith an inner/outer radius ratio r = 0.76, the expected geometry of the molecular hydrogen layer in Jupiter, the bands occupy the region with in +/-45 degrees of the equator. The presence of jets and bands in the se experiments support the conjecture that the zonal winds on Jupiter are maintained by deep convection. (C) 1996 Academic Press, Inc.