An Axisymmetric Limit For The Width Of The Hadley Cell On Planets With Large Obliquity And Long Seasonality

Hadley cells dominate the meridional circulation of terrestrial atmospheres. The Solar System terrestrial atmospheres, Venus, Earth, Mars and Titan, exhibit a large variety in the strength, width and seasonality of their Hadley circulation.

Despite the Hadley cell being thermally driven, in all planets, the ascending branch does not coincide with the warmest latitude, even in cases with very long seasonality (e.g., Titan) or very small thermal inertia (e.g., Mars).

In order to understand the characteristics of the Hadley circulation in case of extreme planetary characteristics, we show both theoretically, using axisymmetric theory, and numerically, using a set of idealized GCM simulations, that the thermal Rossby number dictates the character of the circulation. Given the possible variation of thermal Rossby number parameters, the rotation rate is found to be the most critical factor controlling the circulation characteristics. The results also explain the location of the ascending branch on Mars and Titan.

Ilai Guendelman, Yohai Kaspi
(Submitted on 27 Mar 2019)

Subjects: Earth and Planetary Astrophysics (astro-ph.EP); Atmospheric and Oceanic Physics (physics.ao-ph)
Journal reference: Geophysical Research Letters, 2018, 45, 13213-13221
DOI: 10.1029/2018GL080752
Cite as: arXiv:1903.11656 [astro-ph.EP] (or arXiv:1903.11656v1 [astro-ph.EP] for this version)
Submission history
From: Ilai Guendelman
[v1] Wed, 27 Mar 2019 19:09:54 UTC (1,320 KB)
https://arxiv.org/abs/1903.11656
Astrobiology