ExoPlaSim: Extending the Planet Simulator for Exoplanets

Composite spectra for each of the surface types used in ExoPlaSim. Ground is a mix of fine-grained and solid andesite, basalt, and brown and yellow loam and sand, along with dune sand. Snow and ice types are mixes of snow grain sizes, frost, and clear ice, with the fraction represented by clear ice used as a free parameter to match PlaSim albedos for a 5772 K input spectrum. Spectra are taken from the JPL ECOSTRESS library (Baldridge et al. 2009; Meerdink et al. 2019).

The discovery of a large number of terrestrial exoplanets in the habitable zones of their stars, many of which are qualitatively different from Earth, has led to a growing need for fast and flexible 3D climate models, which could model such planets and explore multiple possible climate states and surface conditions.

We respond to that need by creating ExoPlaSim, a modified version of the Planet Simulator (PlaSim) that is designed to be applicable to synchronously rotating terrestrial planets, planets orbiting stars with non-solar spectra, and planets with non-Earth-like surface pressures. In this paper we describe our modifications, present validation tests of ExoPlaSim's performance against other GCMs, and demonstrate its utility by performing two simple experiments involving hundreds of models. We find that ExoPlaSim agrees qualitatively with more-sophisticated GCMs such as ExoCAM, LMDG, and ROCKE-3D, falling within the ensemble distribution on multiple measures.

The model is fast enough that it enables large parameter surveys with hundreds to thousands of models, potentially enabling the efficient use of a 3D climate model in retrievals of future exoplanet observations. We describe our efforts to make ExoPlaSim accessible to non-modellers, including observers, non-computational theorists, students, and educators through a new Python API and streamlined installation through pip, along with online documentation.

Adiv Paradise, Evelyn Macdonald, Kristen Menou, Christopher Lee, Bo Lin Fan
Comments: 54 pages, 47 figures. Submitted to MNRAS. Model available at this https URL with documentation at this https URL
Subjects: Earth and Planetary Astrophysics (astro-ph.EP); Instrumentation and Methods for Astrophysics (astro-ph.IM)
Cite as: arXiv:2107.07685 [astro-ph.EP] (or arXiv:2107.07685v1 [astro-ph.EP] for this version)
Submission history
From: Adiv Paradise
[v1] Fri, 16 Jul 2021 03:23:52 UTC (21,427 KB)

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