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Venus as an Exoplanet: I. An Initial Exploration of the 3-D Energy Balance for a CO₂ Exoplanetary Atmosphere Around an M-Dwarf Star

Parkinson, Christopher D. and Bougher, Stephen W. and Mills, Franklin P. and Hu, Renyu and Gronoff, Guillaume and Li, Jiazheng and Brecht, Amanda and Yung, Yuk L. (2022) Venus as an Exoplanet: I. An Initial Exploration of the 3-D Energy Balance for a CO₂ Exoplanetary Atmosphere Around an M-Dwarf Star. . (Unpublished)

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The chemical evolution of an exoplanetary Venus-like atmosphere is dependent upon the ultraviolet to near ultraviolet (FUV-NUV) radiation ratio from the parent star, the balance between CO₂ photolysis and recombination via reactions that depend on the water abundance, and various catalytic chemical cycles. In this study, we use a three-dimensional (3-D) model to simulate conditions for a Venus-like exoplanet orbiting the M-dwarf type star GJ 436 by varying the star/planet distance and considering the resultant effects on heating/cooling and dynamics. The simulation includes the middle and upper atmosphere (<40 mbar). Overall, these model comparisons reveal that the impact of extreme ultraviolet to ultraviolet (EUV-UV) heating on the energy balance shows both radiative and dynamical processes are responsible for driving significant variations in zonal winds and global temperature profiles at < 10⁻⁵ mbar. More specifically, CO₂ 15-μm cooling balances EUV/UV and Near InfraRed (NIR) heating at altitudes below 10⁻⁷ mbar pressure with a strong maximum balance for pressures at ~10⁻⁵ mbar, thus explaining the invariance of the temperature distribution at altitudes below 10⁻⁵ mbar pressure for all cases. Our model comparisons also show that moderate changes in NIR heating result in relatively small changes in neutral temperature in the upper atmosphere, and virtually no change in the middle atmosphere. However, with larger changes in the NIR heating profile, much greater changes in neutral temperature occur in the entire upper and middle atmosphere studied.

Item Type:Report or Paper (Discussion Paper)
Related URLs:
URLURL TypeDescription Paper
Parkinson, Christopher D.0000-0002-5722-2224
Bougher, Stephen W.0000-0002-4178-2729
Mills, Franklin P.0000-0002-4270-7333
Hu, Renyu0000-0003-2215-8485
Gronoff, Guillaume0000-0002-0331-7076
Li, Jiazheng0000-0002-2563-6289
Brecht, Amanda0000-0002-9018-6528
Yung, Yuk L.0000-0002-4263-2562
Additional Information:Attribution 4.0 International (CC BY 4.0). CDP would like to acknowledge to James Li and Danica Adams who assisted with the plotting of the figures in this paper. YLY was supported in part by an NAI Virtual Planetary Laboratory grant from the University of Washington. DJA was supported by a NASA FINESST Fellowship.
Group:Division of Geological and Planetary Sciences
Funding AgencyGrant Number
University of WashingtonUNSPECIFIED
NASA Earth and Space Science and Technology FellowshipUNSPECIFIED
Record Number:CaltechAUTHORS:20220524-180247871
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Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:114891
Deposited By: George Porter
Deposited On:01 Jun 2022 17:07
Last Modified:02 Jun 2023 01:25

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