The Formation and Maintenance of the Zonal Winds of Jupiter and Saturn

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94-23305 Marcus Prof. Marcus will model numerically the east-west winds in the upper troposphere (i.e., the visible cloud layer) of Jupiter and Saturn, using 3-D fluid-dynamics. The principal objective is to improve our understanding of why the winds are structured in zones or bands with alternating velocity directions from the equator to the poles. Additionally, the Principal Investigator (PI) will address other unresolved issues of those giant planets' atmospheres -- the number of bands, the magnitude of the wind velocities, the greater velocities of the Saturnian winds compared to the Jovian winds, and the relationship between the winds and the vortices embedded in them. The motivation for the work is that, unlike thermal convection in stars which can be reproduced and studied under laboratory conditions (albeit in simplified form), the mechanism of "east- west" winds of planetary atmospheres has not been modeled in the laboratory and all proposed methods for creating such winds remain mere conjectures. Yet we cannot claim to understand the outer planets until we understand their east-west winds. The PI will base his calculations on two different sets of assumptions: (1) The winds' vertical depth extends over tens of to several hundred density scale heights; and (2) the winds are confined to a thin vertical layer. The point is to decide between the two kinds of theories. The calculations will be done in both spherical and parabolic geometries. The latter geometry has the advantage that a parabolic dish containing a stable fluid overlying a convecting fluid can be built in a laboratory to test the validity of the numerical results, an experiment the PI is suggesting to be carried out by others.