Air Quality Simulation Model Performance for One-Hour Averages

摘要

If a one-hour standard for sulfur dioxide were promulgated, air quality dispersion modeling in the vicinity of major point sources would be an important air quality management tool. It is questioned whether currently available dispersion models would be suitable for use in demonstrating attainment of such a standard in the vicinity of large, elevated, buoyant point sources such as utility power plants. The results summarized in the report suggest that using these models in connection with an hourly average standard does not present the regulatory community with any significant additional uncertainties that are not already being dealt with in connection with the current 3- and 24-hour standards. This review of the results of model evaluation studies was restricted to some fairly simple analyses. Additional analyses are recommended. Recommendations to improve model formulations are made regarding the treatment of plume behavior in the vicinity of the mixing height and the simulation of plume dispersion within the mixed layer during convective conditions.