Clusters of wildfires triggered by intense lightning storms over northern Saskatchewan in late June 2002, and again over central Quebec on 2-3 July 2002 produced a broad coverage of smoke, and particulate matter over much of eastern Canada. At least 85 fires were detected across central Quebec alone in early July, based on the GOES Automated Biomass Burning Algorithm (ABBA) developed at CIMSS/University of Wisconsin-Madison. Satellite imagery also indicated these wildfires intensified rapidly on 5 July in response to dramatic changes in the North American mid- and upper-tropospheric circulation pattern.

The main branch of the mid-level jet experienced amplification across Canada on 4 July resulting in an upper trough over western Canada, a second trough southeast of Hudson Bay, and a mean ridge over Manitoba, and the northern Plains. The eastern trough moved southeast, and developed into a closed low over extreme southeastern Quebec, and northern Maine where it persisted for the next 72 hours. The strengthening cyclonic flow around this upper low, and an intensifying height gradient at 850 mb not only fanned the flames but also provided an effective mechanism for the rapid transport of a thick smoke pall from central Quebec southeastward into the Northeast, northern mid-Atlantic, and adjacent Atlantic Ocean between 5-8 July 2002. Visibility dropped to less than one statute mile in Philadelphia within one hour of the onset of the event as local mixing delivered fire products to the surface layer. The rapid introduction of high concentrations of carbon monoxide, and particulate matter in a major metropolitan area took forecasters and the general public, particularly those susceptible to respiratory ailments, by surprise.

The focus of this study is to examine the synoptic-dynamic sequence of meteorological events that led to the rapid movement of wildfire products, and their harmful impact on local and regional air quality. We will tap the myriad of in-situ data available to describe the event including Pennsylvania’s Department of Environmental Protection, EPA’s AIRNOW, the Maryland Department of the Environment, the Baltimore PM Supersite coordinated by University of Maryland’s Dept. of Chemistry, and the Northeast Oxidant and Particle Study (NEOPS) in Philadelphia. Understanding the atmospheric scenario responsible for rapid transport of natural and anthropogenic materials into a major population corridor is essential to the planning for, and response to any disaster scenario.