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Atmospheric dynamics in high obliquity planets

Lobo, Ana H. and Bordoni, Simona (2020) Atmospheric dynamics in high obliquity planets. Icarus, 340 . Art. No. 113592. ISSN 0019-1035. doi:10.1016/j.icarus.2019.113592.

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Ongoing discoveries of terrestrial exoplanets and the desire to determine their habitability have created an increasing demand for studies of a wide range of climatic regimes and atmospheric circulations. These studies have, in turn, challenged our understanding of our own planet’s atmospheric dynamics and provided new frameworks with which we can further our understanding of planetary atmospheres. In this work, we use an idealized moist general circulation model in aquaplanet configuration to study the atmospheric circulation of terrestrial planets with high obliquities. With seasonally varying insolation forcing and a shallow slab ocean as a lower boundary, we emphasize seasonal phenomena that might not be captured in simulations with annual mean forcing and that might involve nonlinear behaviors. By progressively increasing obliquity, we explore the response of the large-scale atmospheric circulation to more extreme seasonal cycles and a reversed annual mean equator-to-pole insolation distribution, and its impact on the energy and water cycles. We show that for high obliquities, the large-scale atmospheric circulation and the meridional energy transport are dominated by seasonally reversing broad cross-equatorial Hadley cells that transport energy from the summer to the winter hemisphere and significantly mitigate temperature extremes. These overturning cells also play a major role in shaping the planet’s hydrological cycle, with the associated ascending branches and precipitation convergence zones becoming progressively broader and more poleward shifted into the summer hemisphere with higher obliquities. While not embedded within the Hadley cell ascending branches, the hot summer poles of high obliquity planets experience nonnegligible precipitation during and at the end of the warm season: during the summer, lower-level moist static energy maxima at the summer poles force locally enhanced convective activity. As temperatures rapidly drop at the end of the summer and convective activity decreases, the water-holding capacity of the atmosphere decreases and water vapor stored in the atmospheric column rapidly condenses out, extending the duration of the summer pole rainy season into the corresponding autumn. Our study reveals novel understanding of how atmospheric dynamics might influence a planet’s overall climate and its variability.

Item Type:Article
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URLURL TypeDescription
Lobo, Ana H.0000-0003-3862-1817
Bordoni, Simona0000-0003-4771-3350
Additional Information:© 2019 Published by Elsevier Inc. Received 1 April 2019, Revised 21 November 2019, Accepted 3 December 2019, Available online 5 December 2019. We acknowledge financial support from the National Science Foundation, United States of America (AGS-1462544) and from the Caltech Davidow Discovery Fund, United States of America. We thank Yohai Kaspi and Tapio Schneider for helpful comments. The simulations were conducted on the Caltech Division of Geological and Planetary Sciences CITerra high performance computing cluster. The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.
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Davidow Discovery FundUNSPECIFIED
Record Number:CaltechAUTHORS:20191205-163840601
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Official Citation:Ana H. Lobo, Simona Bordoni, Atmospheric Dynamics in High Obliquity Planets, Icarus, Volume 340, 2020, 113592, ISSN 0019-1035, (
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:100215
Deposited By: Tony Diaz
Deposited On:06 Dec 2019 19:01
Last Modified:16 Nov 2021 17:52

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