Unusual ground-level ozone observations in Canada's Rocky Mountain foothills

Ground level ozone concentrations in Alberta, Canada are a result of contributions from various inputs including local photochemistry, long-range transport and stratospheric intrusion. In early May 1998 observations with values three to five times typical maximums were measured at an ambient air monitoring station located in the eastern portions of the foothills of the Rocky Mountains. The incident is examined to identify the potential sources and mechanisms of the sudden increase in ozone. Ambient air monitoring at the observing station and others nearby are analyzed in the context of the larger scale meteorological situation. The source and transport of the ozone is hypothesized from observed and modeled data. Implications for Alberta's ability to achieve new national Canada-Wide Standards are discussed.