3506B24 Final Report
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4 MOTIVATION 4.1 General Observations from the Fall-line Air Quality Study (FAQS) Following concerns that the Augusta, Macon, and Columbus metropolitan areas in Georgia soon would be designated non-attainment for the 8-hour ozone National Ambient Air Quality Standard (NAAQS), the Fall line Air Quality Study (FAQS) was initiated in March 2000 as a multi-year project to assess urban and regional air pollution, identify the sources of pollutants and pollutant precursors, and recommend solutions to realized and potential poor air quality in these metropolitan areas. The study primarily addressed ground-level ozone but ancillary results also provided better understanding of the mechanisms contributing to other pollutants such as fine PM. In order to gain understanding about the fundamental characteristics of air pollution in each city, and to provide state and local officials with additional information that may help enable them immediately to begin planning and implementing measures to mitigate the occurrences of poor air quality, an advanced Mobile Air Quality Research Laboratory (MAQREL) was deployed for intensive measurements of certain trace gas species and meteorological parameters during the summer of 2000 at Macon, Sandy Beach Park (June 11 – 21), Augusta, Fort Gordon (June 25 – July 10), and Columbus, North Water Works facility (July 13 – 23). During those times, additional satellite sites were established at Sandy Beach Park in Macon, Lakeside High School near Augusta, and the Oxbow Environmental Learning Center (OLC) between Columbus and Fort Benning, that continued long-term monitoring of O3 and PM2.5 mass concentrations, including highly sensitive NO, NOy (important ozone precursor species), and a suite of meteorological parameters until October 2003; see http://cure.eas.gatech.edu/faqs/index.html for more details. Figure 4 shows a map of south-central Georgia with overlayed wind rose plots, which are correlations between PM2.5 mass concentration and coinciding wind direction data (based on half hour averages), covering the period January 1, 2001 to December 31, 2002. The data were separated into two periods contrasting the “summer” half of the year, here from May 1 to October 31, shown as red traces, from the “winter” half in blue. In June 2001, a fourth semi-permanent site was established at the University of Georgia Agricultural Experiment Station near Griffin, with the MAQREL serving as advanced monitoring and research platform. The site was chosen with the intension to capture the state and level of pollution of air masses that originated in the metro Atlanta area, as they are being transported southward to Columbus and/or Macon. The fifth wind rose in Fig. 4 represents data collected during the US EPA Atlanta Super-Site Experiment conducted at Jefferson Street in downtown Atlanta during the month of August 1999; see Solomon et al., [2003] for an overview description of this experiment, and Baumann et al. [2003a] for details on the measurements made there with the MAQREL. In general, a wind rose assumes the site as a receptor of air masses, here containing average PM2.5 pollution loads, that arrive from directions indicated in the polar graph. It is important to note, that the wind rose scales are all the same except for the downtown Atlanta site, which is exactly double the others. For comparison, the thin orange circle illustrates the annual NAAQS for [PM2.5] of 15 μg m-3, and the black trace represents the wind direction frequency distribution in percent occurrence of the total two year period. The blue and red numbers next to each rose plot are the average [PM2.5] during calm conditions of the summer and winter halves, respectively. The graph seems to indicate that i) [PM2.5] levels are generally higher in the summer than in the winter, region-wide; ii) highest average [PM2.5] seem to point to larger metro areas, esp. for sites closer in (e.g. Griffin impacted most by northerly flows from Atlanta); iii) metro Atlanta can be considered a potential source for regional impact; and iv) the fine PM levels during calm conditions are surprisingly similar throughout the year but systematically lower in winter. Comparing the seasonal differences with the annual NAAQS (15 μg m-3), it can be clearly seen that the average winter data stay below this threshold region-wide, except for the OLC site between Columbus and Fort Benning. The [PM2.5] rose determined for the OLC site is projected over a more detailed map of the Columbus – Fort Benning region in Figure 5, clearly pointing to a potential source for fine PM in SE directions during winter. In the following we examine the reasons for this observation in more detail. 
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