Atmospheric dynamics of a near tidally locked Earth-sized planet

Abstract

The discovery and characterization of Earth-sized planets that are in, or near, a tidally locked state are of crucial importance to understanding terrestrial planet evolution. For this purpose Venus is a clear analogue. Exoplanetary science lies at the threshold of characterizing hundreds of terrestrial planetary atmospheres, thereby providing a statistical sample far greater than the limited inventory of terrestrial planetary atmospheres within the Solar System. However, the model-based approach for characterizing exoplanet atmospheres relies on Solar System data, resulting in our limited inventory being both foundational and critical atmospheric laboratories. Present terrestrial exoplanet demographics are heavily biased toward short-period planets, many of which are expected to be tidally locked, and also potentially runaway greenhouse candidates, similar to Venus. Here we describe the rise in the terrestrial exoplanet population and the study of tidal locking in climate simulations. These exoplanet studies are placed within the context of Venus, a local example of an Earth-sized, asynchronous rotator that is near the tidal locking limit. We describe the recent lessons learned regarding the dynamics of the Venusian atmosphere and how these lessons pertain to the evolution of our sibling planet. We discuss their implications for exoplanet atmospheres, and outline the need for a full characterization of the Venusian climate to achieve a full and robust interpretation of terrestrial planetary atmospheres. Venus is used as the paradigm of Earth-sized near tidally locked planets. The behaviour and dynamics of its atmosphere are used to gain insight into the climate of terrestrial exoplanets with similar orbital configurations.