On the effects of clouds and hazes in the atmospheres of hot Jupiters: semi-analytical temperature-pressure profiles

TL;DR

This paper develops a semi-analytical model to understand how clouds and hazes influence the temperature-pressure profiles of hot Jupiters, accounting for their dual warming and cooling effects and comparing results with observational data.

Contribution

It introduces a novel semi-analytical formalism that includes clouds/hazes and collision-induced absorption, extending previous models for hot Jupiter atmospheres.

Findings

Cloud/haze effects can cause both warming and cooling in different atmospheric layers.

The model suggests a Bond albedo of approximately 10% for HD 189733b.

The formalism aids in understanding temperature inversions and guides 3D atmospheric simulations.

Abstract

Motivated by the work of Guillot (2010), we present a semi-analytical formalism for calculating the temperature-pressure profiles in hot Jovian atmospheres which includes the effects of clouds/hazes and collision-induced absorption. Using the dual-band approximation, we assume that stellar irradiation and thermal emission from the hot Jupiter occur at distinct wavelengths ("shortwave" versus "longwave"). For a purely absorbing cloud/haze, we demonstrate its dual effect of cooling and warming the upper and lower atmosphere, respectively, which modifies, in a non-trivial manner, the condition for whether a temperature inversion is present in the upper atmosphere. The warming effect becomes more pronounced as the cloud/haze deck resides at greater depths. If it sits below the shortwave photosphere, the warming effect becomes either more subdued or ceases altogether. If shortwave scattering is present, its dual effect is to warm and cool the upper and lower atmosphere, respectively, thus counteracting the effects of enhanced longwave absorption by the cloud/haze. We make a tentative comparison of a 4-parameter model to the temperature-pressure data points inferred from the observations of HD 189733b and estimate that its Bond albedo is approximately 10%. Besides their utility in developing physical intuition, our semi-analytical models are a guide for the parameter space exploration of hot Jovian atmospheres via three-dimensional simulations of atmospheric circulation.