Three-Dimensional Atmospheric Circulation of Warm and Hot Jupiters: Effects of Orbital Distance, Rotation Period, and Nonsynchronous Rotation

Abstract

Efforts to characterize extrasolar giant planet (EGP) atmospheres have so far emphasized planets within 0.05 AU of their stars. Despite this focus, known EGPs populate a continuum of orbital separations from canonical hot Jupiter values (0.03-0.05 AU) out to 1 AU and beyond. Unlike typical hot Jupiters, these more distant EGPs will not generally be synchronously rotating. In anticipation of observations of this population, we here present threedimensional atmospheric circulation models exploring the dynamics that emerge over a broad range of rotation rates and incident stellar fluxes appropriate for warm and hot Jupiters. We find that the circulation resides in one of two basic regimes. On typical hot Jupiters, the strong day-night heating contrast leads to a broad, fast superrotating (eastward) equatorial jet and large day-night temperature differences. At faster rotation rates and lower incident fluxes, however, the day-night heating gradient becomes less important, and baroclinic instabilities emerge as a dominant player, leading to eastward jets in the midlatitudes, minimal temperature variations in longitude, and, often, weak winds at the equator. Our most rapidly rotating and least irradiated models exhibit similarities to Jupiter and Saturn, illuminating the dynamical continuum between hot Jupiters and the weakly irradiated giant planets of our own solar system. We present infrared (IR) light curves and spectra of these models, which depend significantly on incident flux and rotation rate. This provides a way to identify the regime transition in future observations. In some cases, IR light curves can provide constraints on the rotation rate of nonsynchronously rotating planets.

Results from a set of three-dimensional numerical experiments of a hot Jupiter atmosphere

“…Our results have shown that the super-rotating equatorial jet, found as a solution for hot Jupiter atmospheres from several models (see for example Cooper & Showman 2005;Menou & Rauscher 2009;Rauscher & Menou 2010;Heng et al 2011;Dobbs-Dixon & Agol 2013;Parmentier et al 2013;Showman et al 2015;Helling et al 2016;Kataria et al 2016;Lee et al 2016), is robust in our setup. Our model does not include a drag or friction at the bottom boundary potentially responsible for removing some of the dependence on initial conditions (see Liu & Showman 2013;Cho et al 2015).…”

“…Therefore, although much progress has been made (and much more can yet be made) using 1D models, 3D models are required to truly unpick the observations, and extract robust physical meaning. E-mail: nathan@astro.ex.ac.uk Several GCMs (or similar models) with varying levels of sophistication have been applied to hot Jupiters (see for example Cooper & Showman 2005;Cho et al 2008;Menou & Rauscher 2009;Rauscher & Menou 2010;Heng et al 2011;Dobbs-Dixon & Agol 2013;Parmentier et al 2013;Showman et al 2015;Helling et al 2016;Kataria et al 2016;Lee et al 2016), including our own adaptation of the Met Office GCM termed the Unified Model (UM) (Mayne et al 2014a,b;Amundsen et al 2014;Helling et al 2016;Amundsen et al 2016Amundsen et al , 2017Boutle et al 2017). However, much of the progress has been driven by application of a single GCM, the SPARC/MITgcm.…”

Atmospheric Circulations of Hot Jupiters as Planetary Heat Engines

“…Figure 2 shows the change in angular momentum from numerics and Rayleigh drag relative to the change in angular momentum from the Coriolis force, as a function of pressure. We compare both terms against the Coriolis force because it is a small term in the zonal momentum budget of hot Jupiters due to their slow rotation and winds that peak at the equator (Showman & Polvani 2011;Showman et al 2015). In relative terms, we find that the numerical change in angular momentum becomes t > (blue curves).…”

Transitions in the Cloud Composition of Hot Jupiters

“…We discretize the equations on the cubed-sphere grid,as described in Adcroft et al (2004),and use a horizontal fourth-order Shapiro filter in order to smooth horizontal noise (Shapiro 1970). This model has been successfully used to model hot Jupiteratmospheres over the past decade(e.g., Showman et al 2009Showman et al , 2013Showman et al , 2015Lewis et al 2010Lewis et al , 2014Kataria et al 2013Kataria et al , 2015Parmentier et al 2013).…”