Estimating Future-Year Ozone Design Values with Two Regional-Scale Modeling Systems in North Carolina

Across the United States, significantly increased numbers of counties are likely to be designated nonattainment for ozone with the proposed 8-h form of the National Ambient Air Quality Standard (NAAQS). The U.S. Environmental Protection Agency has developed a draft guidance for potential nonattainment areas to demonstrate attainment of the standard through photochemical air quality simulation models. This has led to increased emphasis on the evolution and use of regional-scale models to study longer averaging periods in addressing the complex nature of the tropospheric ozone problem. We have applied two state-of-the-art regional-scale models, the Models-3/Community Multiscale Air Quality (CMAQ) model and the Multiscale Air Quality Simulation Platform (MAQSIP), which was developed as a prototype for CMAQ, to the June 19-30, 1996, O3 episode in North Carolina. Both CMAQ and MAQSIP are fully modularized, three-dimensional modeling systems, with various options for representing the physical and chemical processes for urban- and regional-scale pollution. We have previously compared and presented the relative performance of the two models for base-year modeling for this episode, a period characterized by high ozone in the Charlotte-Gastonia-Rock Hill, Greensboro-Winston Salem