Important

This model is available for academic purposes only. If you require any assistance, please contact us directly.

D-region ion scheme

This is the LIR-ACheM (Lower Ionosphere Region - Absorption & Chemistry Modelling) scheme.

This code works in three steps (more details are in the documentation):

• The initialisation of the ionosphere
• The modelling of the ionosphere from a varying forcing source
• The computation of the HF absorption

This ion scheme is adapted from the six ions scheme from Mitra & Rowe, 1972.

Its main advantages compared to other more complex chemsistry schemes are:

• It is much simpler and numerically efficient
• It has been created for D-region dynamics during solar flares
• All reaction rates are known since the actual species are specified (with the exception of cluster ions and light negative ions)

Please refer to the documentation for information on the scheme and the code used to implement it.

Installation

To install the package, just type:

pip install lir_achem

Please refer to the documentation for examples on how to start using the package.

Documentation

The full documentation is found here.

Testing

To test the entire package, you can run

pytest

This is the minimal version to check that all tests are passed. If, however, you're developping your own branch of the repository, or if you want the coverage report, run:

pytest --cov=lir_achem --cov-report=xml:reports/coverage/coverage.xml
coverage html
genbadge coverage -o reports/coverage/coverage-badge.svg

This will create a full coverage report and a badge to display the new coverage

NOTE: Don't do this if you don't need this. It does take a few minutes to run all the tests.

History

Written by P. Teysseyre and C. Briand (LIRA, Observatoire de Paris, Université PSL, Sorbonne Université, Université Paris Cité, CY Cergy Paris Université, CNRS, Meudon, France) in October 2025 - February 2026

The associated paper is accepted for publication (Teysseyre & Briand, 2026, Atmospheres)