The major air quality concern in the Oklahoma City metro area is ground level ozone pollution. In particular, during the summer months the daily ozone concentrations tend to exceed the NAAQS for ozone and a certain risk exists that Oklahoma City will be assigned as non-attainment area. Although high ozone concentrations are related to precursor emissions in urban areas, ozone pollution is not solely an urban problem. A recent review of findings obtained in a number of European and North American studies clearly indicates that tropospheric ozone pollution is a multi-scale problem extending even up to continental boundaries. As a consequence, ozone concentrations are very sensitive to meteorological conditions on a broad scale range. Key phenomena for understanding of ozone accumulation have been quoted, including extra-urban scale transport winds, vertical structures of wind fields and mixing processes, and mesoscale convergence zones and transport processes. The analysis of wind data clearly indicates that southern wind directions are dominant in the Oklahoma City area. This data prompted to study the impact of long-range pollutant transport from areas south of Oklahoma on local air quality. Of particular interest has been the influence of the urban plume originating in the Dallas -Ft. Worth area.

The paper presents results from a first study, which focused on the analysis of air-quality and meteorological data, in order to verify the hypothesis that long-range transport has a strong influence on ozone pollution in the Oklahoma City metro area. Air quality data from all available Oklahoma monitoring stations have been analyzed for the ozone seasons during 1998-2000 and several, typical week-long ozone episodes have been identified. For each episode the regional weather pattern has been investigated based on synoptic maps, data from the Oklahoma Mesonet and profile soundings. The role of pollutants transport above the nocturnal stable surface layer and subsequent vertical mixing inside the boundary layer will be discussed, as well as regional flow patterns near the surface that are typically associated with high ozone pollution levels. Furthermore, the correlation between ozone pollution levels in the Oklahoma City and Dallas-Fort Worth metro areas has been studied. This analysis further indicates that long-range transport plays an important role in the formation of high ground-level ozone concentrations in the Oklahoma City metro area.