A Comparison of Observed and Simulated 1990 - 2010 U.S. Ozone Trends

摘要

While regional-scale air quality models are routinely used in air quality planning applications to estimate future air quality, these applications typically cover time periods of a year or less. Therefore, the ability of these models to capture observed trends in air quality is rarely evaluated. In this study, we analyze ozone concentrations from long-term (1990 - 2010) WRF-CMAQ simulations driven by year specific meteorology and emissions. These simulations allow us to compare observed and simulated ozone trends in order to evaluate the model's ability to predict changes in air quality given changes in source emissions or meteorology, i.e. dynamic model evaluation. The time period analyzed in this study was characterized by substantial decreases in ozone precursor emissions. A recent study reported trends in observed daily maximum 8-hr (DM8HR) ozone concentrations during the 1998 - 2013 time period at urban, suburban and rural monitors and distinguished between trends in different parts of the ozone distribution and during different seasons. We follow this analysis in our study and also include an analysis of trends in the W126 cumulative ozone exposure metric.