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

Marcus教授将利用三维流体动力学对木星和土星对流层上层（即可见的云层）的东西风进行数值模拟。其主要目的是提高我们对为什么风是在从赤道到两极的速度方向交替的区域或带中形成的理解。此外，首席研究员（PI）将解决这些巨大行星大气的其他未解决的问题——带的数量，风速的大小，土星风的速度比木星风的速度更快，以及风和其中嵌入的漩涡之间的关系。这项工作的动机是，与可以在实验室条件下复制和研究的恒星热对流（尽管是简化形式）不同，行星大气的“东西向”风的机制尚未在实验室中模拟，所有提出的创造这种风的方法都仅仅是猜测。然而，除非我们了解了外行星的东西风，否则我们不能声称了解了它们。PI将基于两组不同的假设进行计算：(1)风的垂直深度延伸到几十到几百个密度尺度高度；(2)风被限制在一个薄薄的垂直层内。关键是要在这两种理论之间做出选择。计算将在球面和抛物线几何中进行。后一种几何结构的优点是，可以在实验室中建立一个包含稳定流体的抛物面盘，覆盖在对流流体上，以测试数值结果的有效性，PI建议由其他人进行这一实验。

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.