Two-Dimensional Models of Microphysical Clouds on Hot Jupiters I: Cloud Properties

TL;DR

This paper introduces a 2D microphysical cloud model for hot Jupiters that accounts for horizontal transport, revealing significant differences from 1D models in cloud distribution, particle size, and chemistry, with implications for observational predictions.

Contribution

The study develops a novel 2D cloud formation model including horizontal transport, providing new insights into cloud dynamics and distribution on hot Jupiters beyond previous 1D approaches.

Findings

Horizontal advection increases cloud formation efficiency.

Cloud distributions become more homogeneous across planets.

Certain clouds survive on daysides where 1D models predict none.

Abstract

We present a new two-dimensional, bin-scheme microphysical model of cloud formation in the atmospheres of hot Jupiters that includes the effects of longitudinal gas and cloud transport. We predict cloud particle size distributions as a function of planetary longitude and atmospheric height for a grid of hot Jupiters with equilibrium temperatures ranging from 1000-2100 K. The predicted 2D cloud distributions vary significantly from models that do not consider horizontal cloud transport and we discuss the microphysical and transport timescales that give rise to the differences in 2D versus 1D models. We find that the horizontal advection of cloud particles increases the cloud formation efficiency for nearly all cloud species and homogenizes cloud distributions across the planets in our model grid. In 2D models, certain cloud species are able to be transported and survive on the daysides of hot Jupiters in cases where 1D models would not predict the existence of clouds. We demonstrate that the depletion of condensible gas species varies as a function of longitude and atmospheric height across the planet, which impacts the resultant gas-phase chemistry. Finally, we discuss various model sensitivities including the sensitivity of cloud properties to microphysical parameters, which we find to be substantially less than the sensitivity to the atmospheric thermal structure and horizontal and vertical transport of condensible material.