Particle and Flames in Radiative and Magnetic Flows

October 11-15, 2010
Lyon, France

Contribution of A.P. Showman


Atmospheric circulation of hot Jupiters




Of the many known extrasolar planets, over 100 have orbital semi-major axes less than 0.1 AU, and a significant fraction of these hot Jupiters and Neptunes are known to transit their stars, allowing them to be characterized with the Spitzer, Hubble, and groundbased telescopes. The stellar flux incident on these planets is expected to drive an atmospheric circulation that shapes the day-night temperature difference, infrared light curves, spectra, albedo, and atmospheric composition, and recent Spitzer infrared light curves seem to show evidence for dynamical meteorology in these planets' atmospheres. Here, I will survey basic dynamical ideas and detailed 3D numerical models that illuminate the atmospheric circulation of these exotic planets. I will describe the dynamical mechanisms for pumping and maintaining the fast jets that develop in these models, particularly the broad eastward (superrotating) equatorial jet that seems to be a near-universal feature of 3D models of synchronously rotating hot Jupiters on 2-4 day orbits. The role of friction in affecting the atmospheric circulation, and the conditions that promote time variability, will also be discussed. I will finish by discussing issues relevant to the atmospheric circulation regimes of super Earths, hot Neptunes, and planets on eccentric orbits. Relevant observational implications and tests will be summarized. Where appropriate, connections to giant planets in our Solar System--Jupiter, Saturn, Uranus, and Neptune--will be emphasized, since these planets provide a foundation for our understanding of giant planet circulation generally.