Do air quality data support the use of UAM-V model use to evaluate control options?

In general, visual comparison of tile maps of measured ozone during modeled episodes with model-predicted ozone values shows that the simulations capture the large-scale features of each episode, suggesting that UAM-V is adequate to evaluate future control options. There appear to be some tendencies for the model to over predict daily maximum ozone levels in the northern portion of the domain and under predict the same for the southern portion of the domain. Further, aircraft measurements taken at selected locations for a few simulation days indicate that ozone levels above the surface layer of the atmosphere may be under predicted by the model. One possible implication of these observations (although not the only one) is that transport impacts may be understated by the model, and this should be kept in mind when interpreting model results regarding transport. Comparison of model predictions to ozone precursor data, while limited by the availability of measurements, shows generally poor agreement, especially for isoprene (from biogenic VOC emissions). Nonetheless, comparison of ozone to total reactive nitrogen ratios in non-urban locations tends to agree with model predictions, again supporting the concept of utilizing model results to evaluate control strategy impacts on regional concentrations (where NOx concentrations typically limit the formation of ozone).