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CheMPAS-A is an MPAS-Atmosphere fork with online, mechanism-configurable chemistry. The atmosphere core couples MPAS transport and meteorology to MUSICA: MICM integrates gas-phase chemistry, TUV-x supplies photolysis rates, and MIEM applies offline emissions.
This wiki documents the CheMPAS-A 26.08 MVP release,
v2026.08.01. It also contains the
namelists, streams files, chemistry configurations, data contracts, and manual
staging instructions needed to reconstruct the example runs. The release also
provides a minimal Docker workflow for
three bounded demonstration cases; the wiki's examples/ tree remains
declarative and contains no run automation.
- Read the CheMPAS-A documentation: User's Guide, tutorial, and developer notes
- Build CheMPAS-A and its pinned MUSICA dependency
- Build and run the three-case Docker workflow
- Stage and launch a first run
- Understand the coupled features and state conventions
- Look up chemistry namelist options
- Choose a reconstructable example
- Reconstruct the global CAMS + FINN emissions experiment
- Acquire and verify the input data
- MICM mechanisms select chemistry species and reactions at run time.
- Runtime MPAS variables expose mechanism tracers, photolysis rates, converted tracer output, and bounded emissions diagnostics.
- Transport and restart files retain dry-air mass mixing ratio as the authoritative chemistry state.
- TUV-x can use MPAS columns with a static or spatially varying prescribed upper atmosphere.
- MIEM can combine exact-grid surface or layered inventories and publish total, sector, category, and layer diagnostics.
- Lightning NOx can use vertical-velocity/altitude or isotherm gating.
- Chemistry cadence, substeps, solver tolerance, failure recovery, and a duplicate reference solve are configurable.
The released examples demonstrate coupling, transport, photolysis, emissions, restart behavior, and source bookkeeping. The reduced mechanisms and idealized initial chemistry fields are not a production atmospheric-composition setup, an operational air-quality forecast, or a chemically assimilated analysis.
CheMPAS-A retains the rest of the MPAS repository. Refer to the MPAS-Atmosphere user guide for standard MPAS initialization, dynamics, physics, streams, and mesh topics.