Characterization of Ambient Ozone Levels in the Great Smoky Mountains National Park

Ambient ozone data collected at two sites in the Great Smoky Mountains National Park (GSMNP) are summarized and compared with data from an urban and a low-elevation rural site. The ozone climatology in the park is found to be similar to that of other remote sites in the southern Appalachian Mountain region. As expected, terrain elevation is identified as a major factor influencing local ozone levels. Episodes of high ozone concentrations (≥90 ppb) in the park are shown to be primarily attributable to the transport of ozone into the park from outside. Backward air trajectories computed for high-ozone episodes in the GSMNP reveal that no preferred source regions exist, although some episodes appear to be associated with transport from urban areas.