Three Worlds in One: Venus as a Natural Laboratory for the Effect of Rotation Period on Atmospheric Circulation

Because of its rotation period of 243 days, Venus is considered a slowly rotating planet. However, its persistent superrotating atmospheric jets, which increase in speed from surface to cloud tops, effectively set a faster rotation speed than the surface rotation. Using the Venus Planetary Climate M...

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Main Authors: Maureen Cohen, James Holmes, Stephen Lewis, Manish Patel, Sébastien Lebonnois
Format: Article
Language:English
Published: IOP Publishing 2025-01-01
Series:The Astrophysical Journal Letters
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Online Access:https://doi.org/10.3847/2041-8213/adade9
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author Maureen Cohen
James Holmes
Stephen Lewis
Manish Patel
Sébastien Lebonnois
author_facet Maureen Cohen
James Holmes
Stephen Lewis
Manish Patel
Sébastien Lebonnois
author_sort Maureen Cohen
collection DOAJ
description Because of its rotation period of 243 days, Venus is considered a slowly rotating planet. However, its persistent superrotating atmospheric jets, which increase in speed from surface to cloud tops, effectively set a faster rotation speed than the surface rotation. Using the Venus Planetary Climate Model and wind measurements taken by the Pioneer Venus entry probes, we show that the Rossby radius of deformation of the atmosphere varies with height. The atmosphere falls into three circulation regimes: (1) from the surface to 20 km, the Rossby radius of deformation exceeds the planetary radius and no Rossby waves form; (2) from 20 to 50 km, the tropical Rossby radius becomes smaller than the planetary radius, and a circulation regime characterized by a superrotating equatorial jet and mid-latitude Rossby gyres appears; (3) from 50 to 70 km, the extratropical Rossby radius becomes smaller than the planetary radius, the jet develops mid-latitude maxima, and the Rossby gyres shift to high latitudes. Studies of exoplanetary circulation regimes as a function of rotation period have repeatedly shown a similar progression. While observing the circulations of exoplanets to confirm these predictions is not currently possible, the presence of different circulation regimes on Venus and their dependence on altitude could be tested by observing campaigns. Such evidence would be the first observational support for the theory connecting differences in planetary rotation periods to circulation regime transitions and would ground predictions of exoplanet circulations in a validated framework.
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spelling doaj-art-1730ac6de2614d2c95929bf0e03cb5fc2025-02-06T17:54:07ZengIOP PublishingThe Astrophysical Journal Letters2041-82052025-01-019801L1110.3847/2041-8213/adade9Three Worlds in One: Venus as a Natural Laboratory for the Effect of Rotation Period on Atmospheric CirculationMaureen Cohen0https://orcid.org/0000-0001-5014-4174James Holmes1https://orcid.org/0000-0003-3018-2135Stephen Lewis2https://orcid.org/0000-0001-7237-6494Manish Patel3https://orcid.org/0000-0002-8223-3566Sébastien Lebonnois4https://orcid.org/0000-0002-2390-8164School of Physical Sciences, The Open University , Milton Keynes, MK7 6AA, UKSchool of Physical Sciences, The Open University , Milton Keynes, MK7 6AA, UKSchool of Physical Sciences, The Open University , Milton Keynes, MK7 6AA, UKSchool of Physical Sciences, The Open University , Milton Keynes, MK7 6AA, UKLaboratoire de Météorologie Dynamique (LMD/IPSL), Sorbonne Université , ENS, PSL Research University, Institut Polytechnique de Paris, CNRS, Paris, FranceBecause of its rotation period of 243 days, Venus is considered a slowly rotating planet. However, its persistent superrotating atmospheric jets, which increase in speed from surface to cloud tops, effectively set a faster rotation speed than the surface rotation. Using the Venus Planetary Climate Model and wind measurements taken by the Pioneer Venus entry probes, we show that the Rossby radius of deformation of the atmosphere varies with height. The atmosphere falls into three circulation regimes: (1) from the surface to 20 km, the Rossby radius of deformation exceeds the planetary radius and no Rossby waves form; (2) from 20 to 50 km, the tropical Rossby radius becomes smaller than the planetary radius, and a circulation regime characterized by a superrotating equatorial jet and mid-latitude Rossby gyres appears; (3) from 50 to 70 km, the extratropical Rossby radius becomes smaller than the planetary radius, the jet develops mid-latitude maxima, and the Rossby gyres shift to high latitudes. Studies of exoplanetary circulation regimes as a function of rotation period have repeatedly shown a similar progression. While observing the circulations of exoplanets to confirm these predictions is not currently possible, the presence of different circulation regimes on Venus and their dependence on altitude could be tested by observing campaigns. Such evidence would be the first observational support for the theory connecting differences in planetary rotation periods to circulation regime transitions and would ground predictions of exoplanet circulations in a validated framework.https://doi.org/10.3847/2041-8213/adade9VenusAtmospheric dynamicsPlanetary atmospheresExoplanet atmospheres
spellingShingle Maureen Cohen
James Holmes
Stephen Lewis
Manish Patel
Sébastien Lebonnois
Three Worlds in One: Venus as a Natural Laboratory for the Effect of Rotation Period on Atmospheric Circulation
The Astrophysical Journal Letters
Venus
Atmospheric dynamics
Planetary atmospheres
Exoplanet atmospheres
title Three Worlds in One: Venus as a Natural Laboratory for the Effect of Rotation Period on Atmospheric Circulation
title_full Three Worlds in One: Venus as a Natural Laboratory for the Effect of Rotation Period on Atmospheric Circulation
title_fullStr Three Worlds in One: Venus as a Natural Laboratory for the Effect of Rotation Period on Atmospheric Circulation
title_full_unstemmed Three Worlds in One: Venus as a Natural Laboratory for the Effect of Rotation Period on Atmospheric Circulation
title_short Three Worlds in One: Venus as a Natural Laboratory for the Effect of Rotation Period on Atmospheric Circulation
title_sort three worlds in one venus as a natural laboratory for the effect of rotation period on atmospheric circulation
topic Venus
Atmospheric dynamics
Planetary atmospheres
Exoplanet atmospheres
url https://doi.org/10.3847/2041-8213/adade9
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