Open Methane

Open Methane is a system for estimating methane emissions over a large area without needing direct measurement.

It uses a system called atmospheric inversion, which produces monthly gridded methane emissions estimates. The inversion works by producing initial bottom-up emission estimates (the prior), simulating the atmosphere and meteorology, and comparing the resulting concentrations with actual atmospheric observations satellites. The inversion corrects the initial estimates iteratively until it finds emissions which produce similar atmospheric methane to the observations.

This repository holds the inversion itself: it converts weather model output into inputs for the CMAQ atmospheric chemistry model, processes TROPOMI satellite observations, and runs a 4D-Var data assimilation using the CMAQ adjoint model to produce posterior emissions estimates.

Open Methane is built for Australia, but can be extended to work in any region. Results are published at openmethane.org.

Getting started

The fastest way to see it work is the Quickstart — a complete run on a small test domain using published Docker images. Nothing to compile.

Then, depending on what you need:

I want to…	Start here
Understand how the pipeline fits together	Overview
Estimate emissions for my own area and time period	Running your own domain
Model an area no existing domain covers	Creating a custom domain
Run without Docker, on a Linux machine	Installing locally
Change the code	Development
Look up a setting, script or output file	Reference
Work out why a run failed	Troubleshooting

Full documentation index: docs/

Related repositories

Running the full pipeline needs two companion repositories, each of which also publishes a public Docker image:

• openmethane-prior — builds the initial (prior) emissions estimate from inventories and land-use data.
• setup-wrf — runs the WRF weather model to produce the meteorology that drives atmospheric transport, and holds the domain definitions.

The CMAQ adjoint model is built in CMAQ-Adjoint and bundled into this repository's Docker image.

[!NOTE] The CMAQ-Adjoint repository and its container image are not public, so the openmethane image cannot be built from source without access. The published images are public and require no credentials. If this affects you, please create an issue or contact us at [email protected].

Contributing

Bug reports and pull requests are welcome. See Development for how to set up, run the tests, and add a changelog entry.

License

Apache License 2.0 — see LICENSE.