Schedule May 09, 2008
Formation of Jets and Equatorial Superrotation on Jupiter
Junjun Liu (Caltech)

Authors: Junjun Liu and Tapio Schneider

The zonal flow in Jupiter's troposphere is organized into alternating retrograde and prograde jets, with a prograde (superrotating) jet at the equator. Existing theories and models cannot account for the jets in an energetically consistent manner. Here we propose that baroclinic eddies generated by differential radiative heating are responsible for the off-equatorial jets, and that equatorial waves generated by intrinsic convective heat fluxes are responsible for the equatorial superrotation. The zonal flow extends downward in the atmosphere, with its speed changing with depth, up to depths at which magnetohydrodynamic drag acts. This is supported by simulations with an energetically consistent general circulation model of Jupiter's outer atmosphere that incorporates radiative processes and intrinsic heat fluxes. The simulations reproduce Jupiter's observed jets and thermal structure and make predictions about as-yet unobserved aspects thereof. The mechanisms proposed likely act in the atmospheres of all giant planets.

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