HR: 0800h
AN: P51B-1427    [Abstracts]
TI: Zonal Winds on Giant Planets
AU: * Glatzmaier, G A
EM: glatz@es.ucsc.edu
AF: University of California, Santa Cruz, Earth Sciences Department EMS Building, Santa Cruz, CA 95064 United States
AB: The deep fluid interiors of giant planets have angular velocities that depend on radius and latitude. Years ago it was proposed that the observed differential rotation on the surfaces of Jupiter and Saturn, i.e., the pattern of alternating zonal winds, is maintained by vortex stretching of convective fluid columns within the deep interiors due to the curvature of the spherical surfaces. This now classic mechanism certainly maintains differential rotation in laboratory experiments of rotating laminar convection of incompressible fluids and in many computer simulations of rotating laminar convection. However, because of the low (eddy) viscosities and high rotation rates of giant planets, this theory predicts extremely thin convective columns (with aspect ratio of order the Ekman number to the 1/3 power). It is highly unlikely that these convective columns exist and remain intact without buckling in the compressible turbulent interiors of giant planets. Here we propose a much more robust mechanism for maintaining differential rotation in such environments based on the local expansion of rising fluid and contraction of sinking fluid. Two dimensional computer simulations of rotating turbulent convection illustrate how the resulting pattern of differential rotation depends on the radial profile of density.
DE: 8147 Planetary interiors (5430, 5724)
DE: 5700 PLANETOLOGY: FLUID PLANETS
DE: 5724 Interiors (8147)
DE: 5744 Orbital and rotational dynamics
DE: 3230 Numerical solutions
SC: Planetary Sciences [P]
MN: 2004 AGU Fall Meeting