Journal cover Journal topic
Geoscientific Model Development An interactive open-access journal of the European Geosciences Union
© Author(s) 2017. This work is distributed under
the Creative Commons Attribution 4.0 License.
Model description paper
02 Nov 2017
Review status
This discussion paper is a preprint. A revision of this manuscript was accepted for the journal Geoscientific Model Development (GMD) and is expected to appear here in due course.
Isca, v1.0: A Framework for the Global Modelling of the Atmospheres of Earth and Other Planets at Varying Levels of Complexity
Geoffrey K. Vallis1, Greg Colyer1, Ruth Geen1, Edwin Gerber3, Martin Jucker2, Penelope Maher1, Alexander Paterson1, Marianne Pietschnig1, James Penn1, and Stephen I. Thomson1 1University of Exeter
2University of Melbourne
3New York University
Abstract. Isca is a framework for the idealized modelling of the global circulation of planetary atmospheres at varying levels of complexity and realism. The framework is an outgrowth of models from the Geophysical Fluid Dynamics Laboratory designed for Earth's atmosphere, but it may readily be extended into other planetary regimes. Various forcing and radiation options are available, from dry, time invariant, Newtonian thermal relaxation to moist dynamics with radiative transfer. Options are available in the dry thermal relaxation scheme to account for the effects of obliquity and eccentricity (and so seasonality), different atmospheric optical depths and a surface mixed layer. An idealized gray radiation scheme, a two-band scheme and a multi-band scheme are also available, all with simple moist effects and astronomically-based solar forcing. At the complex end of the spectrum the framework provides a direct connection to comprehensive atmospheric general circulation models.

For Earth modeling, options include an aqua-planet and configurable continental outlines and topography. Continents may be defined by changing albedo, heat capacity and evaporative parameters, and/or by using a simple bucket hydrology model. Oceanic Q-fluxes may be added to reproduce specified sea-surface temperatures, with arbitrary continental distributions. Planetary atmospheres may be configured by changing planetary size and mass, solar forcing, atmospheric mass, radiative, and other parameters. Examples are given of various Earth configurations as well as a Jovian simulation, a Venusian simulation, and tidally-locked and other orbitally-resonant exo-planet simulations.

The underlying model is written in Fortran and may largely be configured with Python scripts. Python scripts are also used to run the model on different architectures, to archive the output, and for diagnostics, graphics, and post-processing. All of these features are publicly available on a git-based repository.

Citation: Vallis, G. K., Colyer, G., Geen, R., Gerber, E., Jucker, M., Maher, P., Paterson, A., Pietschnig, M., Penn, J., and Thomson, S. I.: Isca, v1.0: A Framework for the Global Modelling of the Atmospheres of Earth and Other Planets at Varying Levels of Complexity, Geosci. Model Dev. Discuss.,, in review, 2017.
Geoffrey K. Vallis et al.
Geoffrey K. Vallis et al.


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Publications Copernicus
Short summary
The atmospheres of Earth and of other planets are extremely complicated, and the models that are used to describe them are also complicated. Although this complication is necessary for such things as weather prediction, it does not help in understanding. Furthermore, when studying other planets, there is insufficient data to warrant the use of complicated models. We have developed a framework that allows the construction of simpler models that allows these atmospheres to be understood.
The atmospheres of Earth and of other planets are extremely complicated, and the models that are...