Evaluation of an Annual Simulation of Ozone and Fine Particulate Matter over the Continental United States – Which Temporal Features are Captured?
Motivated by growing concerns about the detrimental effects of fine particulate matter (PM2.5) on human health, the U.S. Environmental Protection Agency (EPA) recently promulgated a National Ambient Air Quality Standard (NAAQS) for PM2.5. The PM2.5 standard includes a 24-hour limit (65 μg/m3 for the 98th percentile) and annual (15 μg/m3) limit. Except for a few cases, the annual standard will be the primary concern for attainment issues. Over the next several years, grid-based photochemical models such as the Community Multiscale Air Quality (CMAQ) model (Byun and Ching, 1999) will be used by regulatory agencies to design emission control strategies aimed at meeting and maintaining the NAAQS for O3 and PM2.5. The evaluation of these models for a simulation of current conditions is a necessary prerequisite for using them to simulate future conditions. The evaluation presented in this study focuses on determining the temporal patterns in all components of the modeling system (meteorology, emissions and air quality) and comparing them against available observations. Furthermore, we briefly investigated the weekday/weekend differences in the observed and predicted pollutant concentrations and outlined steps for future research. Since anthropogenic emissions are known to have a distinct weekly cycle, such analyses would help us in evaluating the modeling system’s ability to accurately reproduce the observed response to emission changes.
KeywordsOzone Concentration Elemental Carbon Local Standard Time Fine Particulate Matter Baseline Component
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