Understanding the Depths of Brown Dwarfs and Giant Exoplanets: Modelling Substellar Atmospheres

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The main goal of the project is to develop atmosphere models to interpret observations ofexoplanets and brown dwarfs. Both types of objects are described by the same physics. Brown dwarfsare particularly interesting to test various physical processes because this family of object are currently much better observationally constrained than exoplanets. The project will involve the use of state-of-the-art tools develped in Exeter, namely a one-dimensionalatmospheric code ATMO and the three-dimensional UK Metoffice General Circulation Model. The goal is toperform further adaptations of these tools to improve the comparison of models with observations. One first aim is to focuson brown dwarfs and improve our understanding of the role of clouds and other processes in these cool atmospheres.The ultimate goal is to model a large variety of planets, from giant to Earth-like planets. In particular, the coupling between the dynamics and the chemistry is key for a correct interpretation of observations. For now, observational constraints are only available for exoplanets which are strongly irradiated by their parent star, as current observational techniques favour the detection of exoplanets located very close to their parent stars. Photochemical processes therefore play an important role in determining the atmospheric composition, properties of haze and/or clouds and spectroscopic signatures of these planets. Taking those processes into account in a consistent way within a GCM is critical, not only for guiding the future characterisation of potential biosignatures on exo-Earths, but also for the general understanding of exoplanet atmospheres and the interpretation of available observations.