Analysis of Meteorological Factors Influencing Air Quality Model Forecasts of Surface Ozone and PM2.5 During NEAQS-2004

It is well-known that surface temperature and ozone concentrations are highly correlated. This correlation can occur either through the temperature dependence of biogenic emissions and ozone reaction rates, or because surface temperatures are correlated with solar radiation, which has a direct effect on photolysis rates important to ozone formation. Using observational data and Eta-CMAQ and WRF-Chem model forecasts collected during the NEAQS-2004 field program, we examine the complex relation between forecast errors of surface ozone, temperature, and solar radiation. Significant ozone bias errors in the models can be traced to solar radiation bias errors. Using a network of 915-Mhz wind profilers, we also examine the role of boundary-layer depth forecast errors on surface ozone and PM2.5 forecast errors. Finally, using wind profiler observations for case study episodes, we investigate the dependence of wind speed and direction forecast errors on the placement of local maxima of ozone and PM2.5, especially in areas downwind of major metropolitan areas.