THOR 2.0: Major Improvements to the Open-source General Circulation Model

Deitrick, Russell; Mendonça, João M.; Schroffenegger, Urs; Grimm, Simon L.; Tsai, Shang-Min; Heng, Kevin (2020). THOR 2.0: Major Improvements to the Open-source General Circulation Model. Astrophysical journal - supplement series, 248(2), p. 30. Institute of Physics Publishing IOP 10.3847/1538-4365/ab930e

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THOR is the first open-source general circulation model (GCM) developed from scratch to study the atmospheres and climates of exoplanets, free from Earth- or solar-system-centric tunings. It solves the general nonhydrostatic Euler equations (instead of the primitive equations) on a sphere using the icosahedral grid. In the current study, we report major upgrades to THOR, building on the work of Mendonça et al. First, while the horizontally explicit and vertically implicit integration scheme is the same as that described in Mendonça et al., we provide a clearer description of the scheme and improve its implementation in the code. The differences in implementation between the hydrostatic shallow, quasi-hydrostatic deep, and nonhydrostatic deep treatments are fully detailed. Second, standard physics modules are added: two-stream, double-gray radiative transfer and dry convective adjustment. Third, THOR is tested on additional benchmarks: tidally locked Earth, deep hot Jupiter, acoustic wave, and gravity wave. Fourth, we report that differences between the hydrostatic and nonhydrostatic simulations are negligible in the Earth case but pronounced in the hot Jupiter case. Finally, the effects of the so-called "sponge layer," a form of drag implemented in most GCMs to provide numerical stability, are examined. Overall, these upgrades have improved the flexibility, user-friendliness, and stability of THOR.

Item Type:

Journal Article (Original Article)


10 Strategic Research Centers > Center for Space and Habitability (CSH)

UniBE Contributor:

Deitrick, Russell John, Schroffenegger, Urs Andreas, Grimm, Simon Lukas, Heng, Kevin


500 Science > 520 Astronomy




Institute of Physics Publishing IOP




Simon Lukas Grimm

Date Deposited:

09 Mar 2021 14:26

Last Modified:

02 Mar 2023 23:34

Publisher DOI:





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