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Photochemistry of planetary atmospheres with 3D Global Climate Model

Presentation #1045 in the session “Open Engagement Session A”.

Published onMar 17, 2021
Photochemistry of planetary atmospheres with 3D Global Climate Model

The next generation of space and ground-based telescopes (JWST, ARIEL, ELTs) should give us improved transmission/emission spectra for a large diversity of exoplanets, allowing to probe their atmospheric composition. For a better understanding of this data, atmospheric models taking into account photochemistry are required. Several 1D atmospheric models have been developed and can be applied to a diversity of exoplanets. However, taking into account 3D geometry for the analysis can become necessary due to the interplay between atmospheric circulation, chemical kinetics and the potentially very steep temperature gradient between the day and night sides. In particular the terminator is the location of the most important gradient and is the region probed by transmission spectroscopy. This effect becomes very significant on tidally-locked planets like hot Jupiters/Neptunes as well as temperate planets around red dwarfs as the TRAPPIST-1 planets.

In this context we developed a generic (photo)chemical module including photochemistry online for the LMDZ generic 3D Global Climate Model (GCM). Using this new development I will present you our work on atmospheric characterization of exoplanets and early Earth. Thanks to this model we have the possibility to study a wide range of (exo)planets atmospheres. In particular we performed simulation of Trappist-1e atmosphere to observe M-dwarf stellar spectra consequences on Earth like atmosphere. Considering the different stellar UV activity of M-dwarf, photochemistry could be highly impacted. We found that Trappist-1e gather favorable conditions to sustain an ozone layer one order of magnitude more abundant than Earth. Ozone is an important molecule providing a UV shield to protect the surface and potential biological activities. This ozone shield play also a key role in atmospheric dynamic as it is observed on early Earth by triggering the Great Oxidation Event (GOE). Keeping using the GCM we performed simulation to study the GOE on Earth considering potential 3D effect of ozone and on Trappist-1e considering UV activity impact.

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