EXOPLASIM

A range of planets modeled by ExoPlaSim, and postprocessed with SBDART. The top row consists of tidally-locked aquaplanets at T21 orbiting stars ranging from 2500 K to 4000 K, with orbital periods increasing with stellar mass. The bottom row consists of aquaplanets with 24-hour rotation at T42, orbiting stars ranging from 4000 K to 8000 K.

The PlaSim 3D general climate model, extended for terrestrial planets. This model contains the PlaSim GCM, as well as all necessary modifications to run tidally-locked planets, planets with substantially different surface pressures than Earth, planets orbiting stars with different effective temperatures, super-Earths, and more. This model also includes the ability to compute carbon-silicate weathering, dynamic orography through the glacier module (though only accumulation and ablation/evaporation/melting are included; glacial flow and spreading are not), and storm climatology. Future features will include support for multiple celestial light sources (e.g. for a habitable moon orbiting a Jovian planet, or circumbinary planets), coupling with N-body integrators such as REBOUND, and CO2 condensation.

This model ships with a Python API, described below. Full documentation of the API is available at http://exoplasim.readthedocs.io.

Documentation of the original PlaSim model is found in exoplasim/plasim/doc.

ExoPlaSim Python API README

Created by Adiv Paradise

Copyright 2020, Distributed under the General Public License

This API was written with Python 3 in mind, but should work with Python 2 and outdated versions of NumPy.

Requirements

• numpy
• scipy
• matplotlib (only needed for additional utilities)
• GNU C (gcc/g++) and Fortran (gfortran) compilers (for Python utilities)
• (optionally) Other compilers whose use you prefer for the model itself
• (optionally) MPI libraries for those compilers
• netCDF4 (optional)
• h5py (optional)

Compatibility

---

• Linux (tested on Ubuntu 18.04, CentOS 6.10): Yes
• Windows 10: May work with Windows Subsystem for Linux (WSL), testing in progress
• Mac OS X: Yes, requires Xcode and developer tools, and OpenMPI support requires that Fortran-compatible libraries be built. Apple M1 compatibility has not been tested.

Installation

pip install exoplasim

OR:

python setup.py install

The first time you import the module and try to create a model after either installing or updating, ExoPlaSim will run a configuration script.

Multiple output formats are supported by the built-in pyburn postprocessor. If you wish to use HDF5 or NetCDF output formats, you will need the netCDF4-python and h5py libraries, respectively. You can ensure these are included at install-time by specifying them:

pip install exoplasim[netCDF4]

OR:

pip install exoplasim[HDF5]

OR:

pip install exoplasim[netCDF4,HDF5]

You may also configure and compile the model manually if you wish to not use the Python API, by entering the exoplasim/ directory and running first configure.sh, then compile.sh (compilation flags are shown by running ./compile.sh -h).

PlaSim Documentation

Original PlaSim documentation is available in the exoplasim/docs/ folder.

Usage

To use the ExoPlaSim Python API, you must import the module, create a Model or one of its subclasses, call its configure method and/or modify method, and then run it.

An IPython notebook is included with ExoPlaSim; which demonstrates basic usage. It can be found in the ExoPlaSim installation directory, or downloaded directly here.

Basic example::

import exoplasim as exo
mymodel = exo.Model(workdir="mymodel_testrun",modelname="mymodel",resolution="T21",layers=10,ncpus=8)
mymodel.configure()
mymodel.exportcfg()
mymodel.run(years=100,crashifbroken=True)
mymodel.finalize("mymodel_output")

In this example, we initialize a model that will run in the directory "mymodel_testrun", and has the name "mymodel", which will be used to label output and error logs. The model has T21 resolution, or 32x64, 10 layers, and will run on 8 CPUs. By default, the compiler will use 8-byte precision. 4-byte may run slightly faster, but possibly at the cost of reduced stability. If there are machine-specific optimization flags you would like to use when compiling, you may specify them as a string to the optimization argument, e.g. optimization='mavx'. ExoPlaSim will check to see if an appropriate executable has already been created, and if not (or if flags indicating special compiler behavior such as debug=True or an optimization flag are set) it will compile one. We then configure the model with all the default parameter choices, which means we will get a model of Earth. We then export the model configurations to a .cfg file (named automatically after the model), which will allow the model configuration to be recreated exactly by other users. We run the model for 100 years, with error-handling enabled. Finally, we tell the model to clean up after itself. It will take the most recent output files and rename them after the model name we chose, and delete all the intermediate output and configuration files.