Wednesday, 17 January 2007
Development of Case Studies of Regional Poor Air Quality Episodes (Ozone) as Tools for Air Quality Forecasting
Exhibit Hall C (Henry B. Gonzalez Convention Center)
For the past two years, Plymouth State University has been conducting regional case studies of poor air quality due to ozone for different areas of the country. The goal of this project has been to provide a source of background information to meteorologists, many of whom lack expertise in this area, in order to help them to identify relevant synoptic patterns associated with elevated ozone levels. During the first year of the study, the Northeast region was examined. During the second year, the study was expanded to include the remaining area east of the Rocky Mountains. Using the U.S. regional boundaries defined by the National Weather Service as guidelines, five sub-regions were established based upon physical and political boundaries. Utilizing Environmental Protection Agency data and data from additional related sources, the highest daily 8-hour ozone concentrations for numerous stations within each of the five regions were compiled and analyzed to distinguish days when exceedances occurred on a regional level. Specific criteria to each of the regions were then determined to identify cases of high ozone levels according to the Air Quality Index (8-hour concentrations that met “Moderate” or higher levels). The most representative and the most severe cases were then chosen for further analysis. In most of these cases, classic factors such as large areas of high pressure combined with calm winds, clear skies, and a shallow mixing layer were associated with the pollution events, with a passing cold front bringing them to a close. In other cases, the results did not conform to this classic poor air quality pattern. Examples of both types of cases will be presented for different regions.