GEOS-Chem chemistry mechanisms

On this page, we provide an overview of the chemistry mechanisms used in GEOS-Chem.

NOx-Ox-hydrocarbon-aerosol chemistry

The standard NOx-Ox-hydrocarbon-aerosol (aka "full-chemistry") simulation has undergone several updates in recent GEOS-Chem versions. We

Mechanisms in GEOS-Chem v9-01-03 and prior versions

In GEOS-Chem v9-01-03, users could select from one of four pre-defined chemistry mechanisms:

Mechanism	Description	Solvers
standard	NOx-Ox-hydrocarbon-aerosol species (aka "the full-chemistry mechanism")	SMVGEAR, KPP
SOA	NOx-Ox-hydrocarbon-aerosol species PLUS secondary organic aerosol species	SMVGEAR, KPP
Dicarbonyls	NOx-Ox-hydrocarbon-aerosol species PLUS dicarbonyl species	SMVGEAR only
isoprene	NOx-Ox-hydrocarbon-aerosol species PLUS isoprene oxidation products	SMVGEAR, KPP

All of these mechanisms (with the exception of the dicarbonyls simulation) are compatible with both the SMVGEAR solver and the KPP solver. The dicarbonyls mechanism only works with SMVGEAR.

Prior to the release of GEOS-Chem v9-01-03, several new bromine tracers and species were added to the s