Particulate Matter Modeling in the Los Angeles Basin Using SAQM-AERO

ABSTRACT

The SARMAP air quality model, enhanced with aerosol modeling capability, and its associated components were developed to understand causes of ozone (O₃) and particulate matter exceedances in the San Joaquin Valley of California. In order for this modeling system to gain increasing acceptance and use in guiding air quality management, it is important to assess how transportable this modeling system is across geographic domains. We describe the first application of the modeling system outside the “home” domain for which it was developed and evaluated. We have chosen the August 27-28, 1987, intensive monitoring period of the Southern California Air Quality Study to evaluate the performance of the modeling system and to assess its sensitivity to emission control options. The predicted surface concentrations of O₃ and other gas-phase species were spatially and temporally correlated with measured data. The fractional normalized absolute error was 0.32 to 0.36 for O₃, and somewhat larger for other species. The fractional normalized bias for O₃ on August 27 and 28, 1987, was 0.02 to 0.04. The simulated PM_{2 5} mass and constituent species concentrations reproduced the magnitude and variability of the observed daytime concentrations at most locations; however, nighttime PM₂₅ concentrations were over predicted by the model. The model's response to emission control options was consistent with other models of the same genre.