Fast Equivalent Operational Models (FEOMs) for atmospheric chemical kinetics within photochemical air quality simulation models
S.W. Wang, P.G. Georgopoulos
Ozone Research Center, Environmental and Occupational Health Sciences Institute, UMDNJ - R.W. Johnson Medical School and Rutgers University, Piscataway, NJ
Chemical kinetics calculations are often the most computationally intensive components of 3-D Photochemical Air Quality Simulation Models (PAQSMs) such as the Community Multiscale Air Quality model (CMAQ). Various approaches, such as parallel computing and efficient numerical techniques (for example, the sparse matrix vectorized Gear method and the Modified Euler Backward Iterative (MEBI) method), have been introduced to reduce simulation time. This presentation highlights an alternative to the above approaches by creating Fast Equivalent Operational Models (FEOMs) for the chemical kinetics. A FEOM is an expansion of correlated functions which capture the chemical kinetic input-output relationships. From these quantitative input-output relationships, the FEOM calculates efficiently the output species concentrations based on the initial species concentrations, employing very rapid and stable algebraic manipulations. FEOM expansion functions are constructed based on a family of High Dimensional Model Representation (HDMR) tools, which have been implemented as modules of the Modeling ENvironment for TOtal Risk studies (MENTOR) framework. The speed of computations utilizing the FEOM expansion functions offers excellent potential for resolving the computational burden associated with long-term and multi-scenario simulations employing state-of-the-art comprehensive regional and multiscale PAQSMs such as CMAQ. A case study, which focuses on the development of FEOM as an efficient solver for atmospheric chemistry mechanisms (such as CB4) that can be utilized in PAQSMs, is presented here.
Base Funding for the Ozone Research Center is provided by the New Jersey Department of Environmental Protection (NJDEP - Contract AQ05-011). This work is also funded in part by a University Partnership Agreement between the U.S. Environmental Protection Agency (USEPA) and EOHSI. Viewpoints expressed here do not necessarily reflect the views of USEPA, NJDEP, or their contractors.