In addition, policy-relevant summaries and interpretations have been developed and subjected to group reviews in developing this final report. In the paragraphs below, the major policy-relevant results, conclusions and recommendations from the AQA workgroup are presented. In this summary, each category includes policy-relevant questions which are answered with brief statements of pertinent analytical results. In general, these results provide the background assessment of the current ozone problem necessary place the modeling results in the appropriate context. Once one has developed an understanding of this broad perspective, the modeling results can be used to subsequently provide a more focused view of individual episodes and control strategy impacts.
Point sources are generally tall stacks located mostly in rural areas with NOx-rich emissions.
Area source emissions arise mostly from low-level emissions in urban metropolitan areas that are rich in VOC as well as NOx. Temporally, area sources tend to have both a diurnal and seasonal cycle, while point sources are typically more invariant with time. The OTAG region is ventilated typically by prevailing winds coming from outside the domain. The air masses entering the OTAG region originate in Canada in the North and Northeast, from the Gulf of Mexico and Atlantic Ocean in the South, and from the western United States to the Midwest. Ozone concentrations in these air masses are about 30-40 ppb, which corresponds to typical tropospheric background levels measured at remote sites of the world.