Using in situ and satellite observations to track wildfire impacts on ozone and particulate matter in the Pacific Northwest

Biomass burning is a significant source of air pollution that can contribute to poor air quality worldwide. While fires substantially impact surface air quality, they can also loft pollutants into the free troposphere where they are transported over long distances. Understanding the impact of fires is critical given current efforts to tighten air quality standards and the likelihood of increasing fires in a warmer world.

This study uses data collected between 2004-2010 at the Mount Bachelor Observatory (2.7 km asl in central Oregon) to analyze the relationships between fire chemistry, plume height, ozone production and impacts on surface air quality. Plumes from more than fifteen regional and distant fire events are analyzed and the enhancement ratios of aerosol scattering, CO, CO₂ and O₃ are compared. Back trajectories and satellite data, including plume injection heights derived from the Multiangle Imaging SpectroRadiometer (MISR) satellite instrument, are used to identify the fire plumes' transport mechanisms. A preliminary analysis of four 2008 fire plumes showed that plumes with aerosol scattering to CO enhancement ratios lower than 0.6 were lofted between 2000-6000 meters, while plumes with enhancement ratios greater than 0.7 were lofted 3000 meters or less. Data from our June-August 2010 field campaign will build on this analysis by adding CO₂ measurements, which can be used with CO data to understand combustion efficiency. Further, there is a great deal of variability in the degree of ozone production between fire events, with O₃ to CO enhancement ratios ranging from 0 to 0.3. We hypothesize that variations in fire emissions and aging can explain most of these differences.