Numerical air quality forecasts made at NOAA/FSL during NEAQS 2002

The 2002 New England Air Quality Study (NEAQS) was an intensive effort to investigate the chemical and meteorological factors that contribute to poor air quality in the costal New England region. The campaign combined efforts of numerous educational institutions as well as federal, state, and local agencies. Data were collected from an extensive network of ground sites, from the NOAA research vessel Ronald H. Brown, and from the DOE G-1 aircraft. Although many of the ground stations routinely collect data year-round, the period of most intensive measurements was from July 12 through August 10, 2002. This presentation will discuss the configuration and real-time production from numerical guidance in use at NOAA/FSL. The numerical model used during NEAQS is a fully coupled atmospheric and chemistry forecast model (MM5-Chem). The atmospheric model is the Pennsylvania State University/National Center for Atmospheric Research Mesoscale Modeling System Version 5 (MM5). The chemistry model includes the RADM2 chemical mechanism, photolysis, biogenic and anthropogenic emissions and dry deposition. Data analysis is being conducted for three high-ozone events observed along the New England coast, 21 - 22 July 2002, 3-5 August 2002 and 12-15 August 2002. Comparisons are being made between MM5-Chem, observational data and retrospective simulations using other air quality forecast models. The analysis shows that, in general, the various numerical models produce similar results. However, small, but potentially significant, differences in the forecasted boundary layer wind speed and direction, as well as the temperature and moisture profile can result in large differences in regional ozone forecasts. For example, the residual boundary layer originating at the coast of New England and out over the Gulf of Maine was often predicted by MM5 to be warmer, more humid and shallower than what was observed. The resulting temperature and moisture profile is more stable than observed and restricts vertical mixing of pollutants off of the New England coastline.