Planetary Atmosphere Simulator
Athena++/Atmosphere Documentation

What it is

Athena++/Atmosphere is an light-weighted extension of an astrophysical code Athena++ to enable atmospheric simulations. We utilize the static/adaptive mesh-refinement, parallelization, curvilinear geometry, and dynamic task scheduling innate to the Athena++ code and augment it with a multi-fluid hydrodynamic solver that is specially designed for atmospheric flows involving condensible gases, clouds, hazes and precipitation. The purpose of the model is to fascilitate fundamental atmospheric research while maintaining a certain degree of sophistication and reality to explain the real world observation and phenomena.

Why it makes a difference

The current models for simulating atmospheric flows are either too comprehensive or too simplistic. Two examples being the Weather Research and Forecasting Model (WRF) and the Dedalus Project. The former has hundreds of thousands of lines of code that meet the needs of all kinds of research regarding Earth's atmosphere. The latter is essentialy a PDE solver with boundary conditions, which is perfect for fundamental studies but is too primitive for explaining real world phenomena.

The Athena++/Atmosphere model sits in between. It can be either regarded as a fully-compressible hydrodynamic solver for idealized atmospheric simulations, or a realistic modeling tool for planetary atmospheres including radiative transfer, cloud microphysics and photochemistry. In this sense, a suit of hierarchical models can be achieved using the same framework, allowing progressive sophistication and specialization. It is light-weighted, meaning that the core part of code are less than 10k lines, thanks to a modern C++ design. An inexperienced user can get it running and understand the underpinning of the solver system within a few weeks of time.

Mission and vision

We are having too many codes and too few documentations on how to actually modify them for our own purpose. Basically, we are sold of a vehicle but without manuals on understanding the internal mechanism that drives the vehicle. Or, the interal logic is too sophisticated to be understood in a reasonable amount of time. It is then our mission to provide well-documented and simple tools to enable BUILDING atmospheric models for YOUR OWN PURPOSE that can run from laptops to supercomputers. We hope to create an open, inclusive, participatory community working on a state-of-the-art and modern software gadgets that constitutes the go-to solution for innovative ideas.


The model is designed to be installed as easy as possible, from a personal laptop to a giant computation cluster. Asuming that you work with a Unix/linux system, obtain a public version of the code via the following command:

git clone

If you wish to have access to the development version of the code, please contact the author Cheng Li.

You will need the following packages for running in serial. If your package management system is apt, with sudo privilege you can obtain them via:

sudo apt install libnetcdf-dev
sudo apt install netcdf-bin
sudo apt install nco

For parallel runs, you will need the MPI libraries:

sudo apt install libopenmpi-dev
sudo apt install openmpi-bin
sudo apt install libpnetcdf-dev

Finally, install the required python packages. If you already have pip3 installed, go to the root directory of the code and execute:

pip3 install -r requirements.txt

Otherwise, obtain pip3 first by:

sudo apt install python3-pip

Congratulations! You have installed all necessary packages. Now move on to the next session on how to get started.

Getting started

The best way to get started is to work with an example. We provide a detailed documentation of an example problem in which we calculate the propagation of a density current on the surface. The introduction, commented program and results are located at page Example #1 : The 2d.straka Problem. The documentation is written in such a way that focuses on explaining what's going on in individual code blocks. Understanding this program serves as a basis for understanding the internal mechanism of the code.

Citing our work

If you feel that our code helps your project, please consider citing our work in your publication:

  1. Huazhi Ge, C. Li, X. Zhang, D. Lee, 2020, A Global Nonhydrostatic Atmospheric Model with a Mass-and Energy-conserving Vertically Implicit Correction (VIC) Scheme, ApJ, 898.2:130
  2. Cheng Li, X. Chen, 2019, Simulating Non-hydrostatic atmospheres on Planets (SNAP): formulation, validation and application to the Jovian atmosphere ApJS, 240.2:37
  3. Cheng Li, T. Le, X. Zhang, 2018, A High-performance Atmospheric Radiation Package: with applications to the radiative energy budgets of giant planets, JQSRT, 217
  4. Cheng Li, A. Ingersoll, F. Oyafuso, 2018. Moist adiabats with multiple condensing species: a new theory with application to giant planet atmmosphere, JAS, 75(4)


There are a variety of ways to contribute. The simpliest way is to send us your problem generator file, the input file and a sample output file so that we can reproduce your results. We will make documentations out of it and deploy it to the project website so that your effort will be recognized and shared among the community.