Clouds as the driver of variability and colour changes in brown dwarf atmospheres

TL;DR

This study demonstrates that clouds are a key factor driving variability, spectral changes, and atmospheric dynamics in brown dwarf atmospheres, using advanced 3D climate modeling.

Contribution

The paper introduces a comprehensive 3D climate model including cloud processes, revealing clouds' crucial role in brown dwarf atmospheric variability and the L/T transition.

Findings

Cloud radiative effects induce atmospheric convection.

Spectral, spatial, and temporal variability observed in models.

Low latitudes show wave activity; higher latitudes dominated by eddies.

Abstract

Brown dwarfs are massive, giant exoplanet analogues subject to variability and colour changes, known as the L/T transition, fundamental for their thermal evolution. The drivers of the L/T transition remain elusive, with atmospheric circulations and/or clouds usually suggested as potential mechanisms. Using a three-dimensional Global Climate Model including cloud formation, transport and multi-wavelength radiative effects, we show that clouds play a major role in shaping the atmospheric properties of brown dwarfs. Cloud radiative effect, which triggers atmospheric convection, leads to spectral, spatial, and temporal variability in the modelled brown dwarfs, in agreement with the observed variability and L/T transition. Low latitudes are subject to sustained wave activity, whereas eddies dominate higher latitudes. Our results highlight that the role of clouds as a driver of atmospheric dynamics and climate, well known for giant exoplanets, extends to all sub-stellar bodies.