The Effect of Planetary Rotation Period on Clouds in a Global Climate Model with a Bin Microphysics Scheme
Clouds are the largest source of uncertainty in climate simulations. For exoplanets, cloud simulation is particularly challenging because of the lack of observational data to tune parameterized cloud models.
Here we apply Community Aerosol and Radiation Model for Atmospheres (CARMA), a size-resolved bin cloud microphysics model, to the atmospheric global climate model Community Atmosphere Model (CAM6) and simulate exoplanets with a range of planetary rotation rates.
CARMA produces fewer liquid clouds than the native CAM6 parameterized cloud microphysics scheme (Morrison-Gettelman two-moment microphysics, MG), more ice clouds, and a significantly different ice cloud size distribution.
Overall, this leads to a decrease in the magnitude of the net CRE by 4-10 W/m2, which is unlikely to change the determination of habitability from a climate perspective in most cases. The difference in ice cloud size distribution is likely to strongly affect transmission spectral retrievals.
Our work confirms that the MG parameterized cloud microphysics scheme can produce reasonable climate simulation when extrapolated to some exoplanet contexts and highlights the value of resolved cloud microphysics for evaluating parameterized schemes and for interpreting observations.
Huanzhou Yang, Eric T. Wolf, Cheng-Cheng Liu, Yunqian Zhu, Owen B. Toon, Dorian S. Abbot
Comments: 8 pages, 7 figures, published in ApJ
Subjects: Earth and Planetary Astrophysics (astro-ph.EP)
Cite as: arXiv:2603.03767 [astro-ph.EP] (or arXiv:2603.03767v1 [astro-ph.EP] for this version)
https://doi.org/10.48550/arXiv.2603.03767
Focus to learn more
Journal reference: ApJ 999 184 (2026)
Related DOI:
https://doi.org/10.3847/1538-4357/ae40b5
Focus to learn more
Submission history
From: Huanzhou Yang
[v1] Wed, 4 Mar 2026 06:24:43 UTC (1,007 KB)
https://arxiv.org/abs/2603.03767
Astrobiology,
