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Patchy clouds on the nightsides of ultra-hot Jupiters

Presentation #102.420 in the session Poster Session.

Published onJun 20, 2022
Patchy clouds on the nightsides of ultra-hot Jupiters

The atmospheres of ultra-hot Jupiters have been characterized in detail through recent phase curve and low- and high-resolution transmission and emission spectroscopy observations. These observations have found that the daysides of ultra-hot Jupiters are likely hot enough to be cloud-free and their nightsides are not uniformly cloudy, as expected for cooler hot Jupiters. Recent three-dimensional modeling of ultra-hot Jupiter atmospheres with clouds either coupled to the dynamics or post-processed have found that the nightsides of ultra-hot Jupiters are likely partially covered by a patchy cloud deck of high-temperature condensates and silicates. In this work, we study the patchy cloud coverage in ultra-hot Jupiter atmospheres with the three-dimensional ultra-hot Jupiter MITgcm coupled to radiatively and dynamically active cloud tracers. To determine our cloud condensate properties, we simulate the dominant species from CARMA cloud microphysics models along with their approximate cloud particle size distribution, single scattering albedo, and asymmetry parameter. We model the newly discovered ultra-hot Jupiter TOI-1431b, which has an equilibrium temperature of 2370 K and an inflated radius typical of ultra-hot Jupiters. We conduct a suite of GCM simulations varying cloud microphysical and scattering properties and gas opacity, and find that partial cloud coverage on the nightside and western limb is a ubiquitous outcome of our models in the parameter regime considered. We find that condensate clouds on the nightside and western limb are sequestered at depth due to a thermodynamically driven thermal inversion as atomic hydrogen recombines to molecular form, warming the nightside atmosphere at low pressures. We study the vertical transport of condensate clouds, finding that the patchy spatial distribution of cloud tracers does not directly track the local temperature conditions in the atmosphere. Rather, the cloud distribution is set by vertical mixing driven by the large-scale atmospheric dynamics, necessitating a coupled understanding of cloud formation and transport to predict the patchy cloud coverage of ultra-hot Jupiters. We post-process these GCMs with the gCMCRT Monte Carlo radiative transfer model in order to both compare our results with the observed TESS phase curve of TOI-1431b and make observational predictions for JWST characterization of the patchy cloud coverage of ultra-hot Jupiters.

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