Recorded presentation6.6
Formation mechanisms of jets and superrotation on giant planets
Junjun Liu, Caltech, Pasadena, CA; and T. Schneider
The atmospheres of the giant planets exhibit alternating prograde (eastward) and retrograde (westward) jets of different strengths and widths, with a prograde equatorial jet (superrotation) on Jupiter and Saturn and a retrograde equatorial jet (subrotation) on Uranus and Neptune. The jets are driven by differential radiative heating of the upper atmosphere, by intrinsic heat fluxes emanating from the deep interior, or by a combination of the two. However, existing models cannot account for the different flow configurations on the giant planets in an energetically consistent manner. Here we use simulations with a three-dimensional general circulation model to show that the different flow configurations can be reproduced by mechanisms universal across the giant planets if one takes into account their different radiative properties and strengths of intrinsic heat fluxes. Whether the equatorial jet is prograde or retrograde depends on whether the deep intrinsic heat fluxes are strong enough to overcome radiative stabilization so that convection penetrates into the upper atmosphere. The different strengths and widths of the off-equatorial jets depend, among other factors, on the thermal stratification of the atmosphere and the altitude of the jets. The simulations make predictions about aspects of the flow and temperature structure of the giant planets that have not been observed yet.
Session 6, Atmospheric and Oceanic Fluid Dynamics Modeling II
Wednesday, 10 June 2009, 10:20 AM-12:20 PM, Pinnacle BC
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