AAAR 37th Annual Conference October 14 - October 18, 2019 Oregon Convention Center Portland, Oregon, USA
Abstract View
Airborne Characterization of Wildfire Influence on Local Air Quality in California
Nilima Sarwar, Walt Williams, Armin Sorooshian, Haflidi Jonsson, Richard Flagan, John Seinfeld, ANDREW METCALF, Clemson University
Abstract Number: 212 Working Group: Biomass Combustion: Emissions, Chemistry, Air Quality, Climate, and Human Health
Abstract In many regions, wildfires contribute significantly to airborne particulate matter. Many factors influence the degree to which these fires affect local air quality, including fire size, fuel type, stage of the fire, meteorology, and co-located pollution sources. In early summer of 2018, several wildfires were encountered in Northern California which influenced air quality in the San Francisco Bay and Sacramento Valley areas. These areas were sampled by the Naval Postgraduate School’s Twin Otter aircraft, which was instrumented with a payload focused on aerosol characterization. The payload included multiple aerosol size and optical property measurements, aerosol chemical composition by an aerosol mass spectrometer, and black carbon (BC) aerosol by a Single Particle Soot Photometer (SP2).
In this talk, these aerosol measurements are used to assess the influence of two wildfires on the background air in the region. One fire, the County Fire, was a ~90,000 acre fire and was sampled several days after it was ignited and well before it was fully contained. The second fire, the Pawnee Fire, was much smaller, at ~15,000 acres, and was sampled on the last day of its active burning. Noticeable differences in the vertical extent of each plume and the ease with which each plume was identified were seen in the BC and total aerosol number and mass concentrations. Particle size distributions are analyzed to separate the urban from biomass burning plumes. Finally, aerosol composition measurements of the biomass plumes align well with expected values from lab studies of combustion with similar fuels. These two wildfire case studies provide contrasting examples of the influence wildfires can have on local air quality.