Mathematical modeling of photochemical air pollution—III. Evaluation of the model

Abstract

The results of model evaluation exercises carried out for the urban airshed model developed in Parts I and II are presented. Concentrations of CO, hydrocarbons, NO, NO₂ and O₃ in the Los Angeles airshed were simulated for 6 days in the fall of 1969. Prior to carrying out these simulations, rate constants and stoichiometric coefficients used in the kinetic mechanism that has been incorporated in the airshed model were determined by separately validating the kinetic mechanism with laboratory smog chamber data for several hydrocarbon-NO_x, systems, including auto exhaust. In addition, to take into account the effect of local sources on concentrations measured at certain Los Angeles County Air Pollution Control District monitoring stations, a simple microscale model was developed. This model was used to predict the local effect of a heavily-travelled roadway on concentrations measured at a near-by monitoring station. The overall results exhibit good enough agreement with the monitoring data to suggest that in the future air pollution models based on representation of actual physical and chemical processes can be important components of abatement strategy planning.