Atmospheric convection

Two side-by-side 3D visualizations of a planet. The left panel displays 3D convective clouds with a grid overlay on one side of the planet, and black arrows indicating wind direction and strength. The right panel shows similar features from a different angle, highlighting the distribution of clouds and wind vectors.

Convection is a major driver of energy transport in planetary atmospheres. It is a key process in the formation of clouds and precipitation. I use high-resolution models to resolve convective dynamics on Earth-like planets and sub-Neptunes.

Three grayscale maps compare outgoing longwave radiation from a climate model for the exoplanet TRAPPIST-1e. The left panel shows a global map with a blue rectangle highlighting a zoomed region. The middle panel displays a pixelated close-up of the highlighted area. The right panel presents a high-resolution simulation of the same region, revealing swirling cloud patterns. A vertical color bar on the right is labeled TOA OLR in watts per square metre and ranges from 70 to 260.

Characterising exoplanets in terms of their potential habitability and the detectability of their atmospheres relies on physically justified modelling of cloud processes. Directly related to cloud formation is moist convection. With sufficient model resolution, convection can be simulated explicitly without relying on approximations, thus improving the accuracy of exoplanetary climate predictions. In my 2020 study1, I performed such convection-resolving simulations using the Unified Model for temperate Earth-sized planets, using TRAPPIST-1e and Proxima Cenatauri b as possible examples. My simulations indicate that the transport of energy and material from the day hemisphere to the night hemisphere is markedly different when convection is directly resolved.

Using the new model of the Met Office, LFRic, I showed that convection can be resolved in a stretched-mesh configuration2, which captures the key feedback between convection on the day side and the global climate of the planet.

1.
Sergeev, D. E., Lambert, F. H., Mayne, N. J., Boutle, I. A., Manners, J. & Kohary, K. Atmospheric Convection Plays a Key Role in the Climate of Tidally Locked Terrestrial Exoplanets: Insights from High-resolution Simulations. The Astrophysical Journal 894, 84 (2020).
2.
Sergeev, D. E., Boutle, I. A., Lambert, F. H., Mayne, N. J., Bendall, T., Kohary, K., Olivier, E. & Shipway, B. The Impact of the Explicit Representation of Convection on the Climate of a Tidally Locked Planet in Global Stretched-mesh Simulations. The Astrophysical Journal 970, 7 (2024).