We are two high schoolers who would like to embark on a project to simulate the atmospheres of exoplanets.

More specifically, we would like to change the atmospheric composition of such planets. We have seen various climate models, such as CESM and PlaSim. Unfortunately, CESM appears to be quite complex, while the latter option doesn't have the resources we would need.

Are there any other simulators that may consistently do the same thing, but need lower computer specifications? Otherwise, are there any resources to become familiar with CESM at a high school level?

Furthermore, what would be the required specifications for running CESM on a fairly consistent basis? I have heard that you would need a cluster, but we currently do not have access to one. We may be able to rent one out, but we'd rather be familiar with CESM before we do.

Thank you!

EDIT: (for clarification) I know a bit of FORTRAN, and have access to help from a Physics instructor. Although I understand that it may be out of the reach of two high school students, is there any sort of "crash course", one could recommend on more advanced astronomical physics?

Furthermore, we are interested in a rocky exoplanet, and potentially have access to a cluster/help from a professor.

Thank you once again!

  • $\begingroup$ What kind of exoplanets are you interested in? Rocky or rather gassy? I can give you names of some exoclimes (like the Swiss exoclime.net) platform, but as @Baroclinic pointed out, this won't help you. Either you go simple, 0-dimensional, or you go for the whole thing, and then you need a cluster and a physics degree to know what you're doing. $\endgroup$ Commented Jul 21, 2017 at 22:07

2 Answers 2


I think there's stuff out there that you can use. The key is searching for "intermediate complexity models", or "toy atmosphere models" (where toy is science jargon for simple model that does things qualitatively right, but not useful for precise quantitative prediction).

In terms of your question "are there any other simulators that consistently do the same thing", I'm not sure what you mean.. do you mean a simulator that will produce the same solution/climate state for the same set of initial conditions?

For the question "what would be the required specifications for running CESM on a fairly constant basis?", that's going to depend on how complex of a simulation you set up. For example, if you are running a detailed simulation (high spatial and/or temporal resolution) and you want to have data for multiple variables at every grid cell through time, then you'll need supercomputing resources. If you were able to get access to one, you usually have to reserve time a few months in advance, run your simulation, and hope it worked out. With cluster computing, you would have to reduce the simulation size (compared to the supercomputer example), but you'd get more freedom to run multiple simulations.

Here is a small list of less computationally intensive and self-contained models

1) The first is called fast climate and is written in matlab code. I know nothing about it, but it looks to be self-contained.

2) Also i just came across a GCM that claims to be user friendly called EDgcm. I know nothing about it, but it looks worth digging into.

3) There's an intriguing app called "GCM" I've honestly never messed around with it, but it could be worth a shot.

4) Here's an energy balance climate model that can be executed in excel.

If you're determined to use a GCM, I think you could probably get CESM working using either the aquaplanet or dry dynamical core setups. Depending on how simple you set it up, you could likely run it just on a standard PC. Another option you have is MITgcm, which can also be configured to run very bare-bones simulations that don't require much computational power.

If you have a university near you, I would consider seeing if there are any climate modeling groups, and reach out to see if there are any grad students willing to lend a little support. I know grad students who spend usually the first semester of their phd trying to get a simulation going.


Unfortunately, I don't think such a numerical model exists that would be suitable for high school students' understanding. The simplest climate model around is a zero-dimensional (energy balance) climate model, but a background on mathematics, and programming may be necessary. You can find one here. Wikipedia has one listed. Michael Mann has the source code for such a model, but it is written in MATLAB (you may be able to run it in OCTAVE, since MATLAB is licensed). There are likely many more than just these, considering multiple layers, volcanic eruptions, etc.

The code for the models listed are simplified models that do not consider things like clouds, aerosols, eddy diffusion, etc. This is where Global Climate Models (GCMs) differ. They must consider how fine details, some of which aren't considered by weather models, affect the climate. Therefore, they are usually complicated. Most GCMs I have seen are written in FORTRAN, which is an antiquated language, but computationally efficient. This makes even easy concepts obtuse.

While I have not dealt specifically with CESM, I can infer some things about it. By definition, CESM is an earth systems model, not an exoplanet model. You may be able to adapt some of the parameters to other planets, but it becomes too difficult for just one person to do (because of FORTRAN). There are models for other places, such as GCMs for Mars, but they are difficult to run and not necessarily accurate. Clusters are needed due to memory limitations, and how long they run for.

  • $\begingroup$ Hi! Thank you for the response, but I had a quick question about CESM. We currently do have access to a configuration which suited the type of exoplanets we were studying, namely ones around M-Dwarfs. Would you still recommend attempting it, or instead going for an easier way. We both have a strong background in math and programming as well. $\endgroup$ Commented Jul 23, 2017 at 0:10
  • $\begingroup$ What aspects are you looking for? If you are looking for simple things like temperature, I'd still suggest 0-dim models. If you truly want to modify CESM for your studies, you are more than welcome to do so, but you will run into a variety of problems. These include, but aren't limited to problems with axial tilt, length of days, composition (Mars, for example, has its atmosphere becomes solid at the poles), surface roughness (if applicable), non-water cloud formation, dust, eddy transport, etc. $\endgroup$ Commented Jul 23, 2017 at 1:27

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