3H: Model Independent Chemistry Module (MICM) Development

ACOM scientists and software engineers began development of the Model Independent Chemistry Module (MICM). The goal of the project is to create a chemistry module that can be implemented in any atmosphere model used at NCAR. This will enable scientists to use and contribute to a state-of-the-art atmospheric chemistry package for local, regional and global studies, and use multiple models using the same chemistry for investigating topics like seasonal air quality prediction or urban air quality prediction. 

MICM is making use of the recently developed ACOM database of atmospheric gas-phase and heterogeneous reactions to provide a list of chemical reactions, including their thermodynamic and photodissociation rate constant data, as well as characteristics of the trace gases and aerosols. This information is being generated into Fortran code that will solve the set of ordinary differential equations describing the chemistry, based on the environmental conditions, such as temperature, pressure, humidity, provided by the atmosphere model. This work flow is drawn in Figure 1.

Model Independent Chemistry Module (MICM)
Figure 1. Model Independent Chemistry Module (MICM). Click for larger image.

ACOM software engineers have created a prototype stand-alone box model, MusicBox. MusicBox provides environmental data and computes simple chemical reaction kinetics for the “box”. The code is being refined to demonstrate MICM with the Chapman chemistry (comprised of 5 reactions, with both photolysis and thermal gas-phase reactions) and any set of chosen gas-phase reactions.

ACOM scientists and software engineers have also been working with the UCAR community to foster collaborations for the development of the MUSICA model, which will be a global model with regional refinement such that studies on the effects of local pollution on regional and global scales, as well as global-scale phenomena (e.g. El Nino) effects on local pollution, can be studied. In late July 2018, NCAR/ACOM modelers met with counterparts from the GEOS-Chem community to begin collaborations for the planned MUSICA model.