A reaction represents a transformation of the model state due to a physical or chemical process that occurs within a phase (gas or aerosol) or across the interface between two phases. In the camp-chem model, reactions are grouped into mechanisms, which are solved over time-steps specified by the host model.

The primary function of a reaction in the camp-chem model is to provide the solver with contributions to the time derivative and Jacobian matrix for chemical species concentrations based on the current model state described in a camp_camp_state::camp_state_t object.

Specific reaction types extend the abstract camp_rxn_data::rxn_data_t type and generally accept a set of reactants and products whose names correspond to chemical species names, as well as a set of reaction parameters needed to describe a particular reaction. During initialization, a reaction will have access to its set of parameters as well as the parameters of any species and aerosol phase in the camp-chem model, however this information will not be available during a model run. The information required by the reaction instance to calculate its contribution to the time derivatve and Jacobian matrix must therefore be packed into the condensed data arrays of the camp_rxn_data::rxn_data_t object during intialization.

Valid reaction types include:

The general input format for a reaction can be found here.