A photochemical model for air quality assessment: Model description and verification

A hybrid Eulerian-Lagrangian, photochemical model has been developed for the assessment and prediction of the impact of large point sources on air quality. This simple model is based on solving the mass conservation equations which include chemical reaction terms in the cells of a two-dimensional crosswind plane which moves with the air parcel. Testing of the model is done in three ways. First, the chemistry is evaluated using results of smog chamber experiments simulating Melbourne's emissions and meteorological conditions. Second, the accuracy of the emissions inventory is tested using aircraft measurements. Finally the overall performance of the model is evaluated using monitoring station data. In general the model gives good agreement with the measurements, with the predictions for O₃ being somewhat better than those for NO₂. This result was also found in the three-dimensional study of McRae and Seinfeld (1983, Atmospheric Environment17, 501–522) for the Los Angeles area.