Mathematical Modeling of the Formation of Nitrogen-Containing Air Pollutants. 1. Evaluation of an Eulerian Photochemical Model

A grid-based, Eulerian airshed model has been used to study the formation and control of gas- and aerosol-phase nitrogen-containing air pollutants. The performance of the model was assessed by comparison against field measurements made for this purpose in the Los Angeles area over the period 30-31 August 1982. Model predictions for O_3 and peroxyacetyl nitrate (PAN) concentrations are in good agreement with observations. The absolute values of the total inorganic nitrate, NH_3, and HNO_3 predictions on the average are within a few ppb of the observations. Lacking an inventory of ionic and alkaline aerosol emissions, accurate apportionment of total inorganic nitrate between the aerosol and gas phases is not possible at coastal locations. At midbasin sites like Anaheim, where NH_4NO_3 is the dominant nitrate aerosol species present, the aerosol nitrate levels predicted by the model are in good agreement with observed values.