Title: Atmospheric Circulation and Cloud Evolution on the Highly Eccentric Extrasolar Planet HD 80606b,
Abstract: Observations of the highly-eccentric (e~0.9) hot-Jupiter HD 80606b with
Spitzer have provided some of best probes of the physics at work in exoplanet
atmospheres. By observing HD 80606b during its periapse passage, atmospheric
radiative, advective, and chemical timescales can be directly measured and used
to constrain fundamental planetary properties such as rotation period, tidal
dissipation rate, and atmospheric composition (including aerosols). Here we
present three-dimensional general circulation models for HD 80606b that aim to
further explore the atmospheric physics shaping HD 80606b's observed Spitzer
phase curves. We find that our models that assume a planetary rotation period
twice that of the pseudo-synchronous rotation period best reproduce the phase
variations observed for HD~80606b near periapse passage with Spitzer.
Additionally, we find that the rapid formation/dissipation and vertical
transport of clouds in HD 80606b's atmosphere near periapse passage likely
shapes its observed phase variations. We predict that observations near
periapse passage at visible wavelengths could constrain the composition and
formation/advection timescales of the dominant cloud species in HD 80606b's
atmosphere. The time-variable forcing experienced by exoplanets on eccentric
orbits provides a unique and important window on radiative, dynamical, and
chemical processes in planetary atmospheres and an important link between
exoplanet observations and theory.