Evolution of Black Carbon upon Coating with Biomass Burning Organic Aerosol

CHRISTIAN ESCRITT, Katrina Betz, Micah Miles, Elijah Schnitzler, Oklahoma State University

     Abstract Number: 364
     Working Group: Carbonaceous Aerosols

Abstract
As the instances of severe wildfire increase across much of the US, the interactions between emissions of biomass burning and urban sources at the wildland-urban interface become more critical to air quality and climate change. In the urban environment, uncoated aggregates of black carbon (BC) are commonly emitted from diesel engines used in transportation. When biomass burning emissions are transported across the wildland-urban interface, these BC aggregates are exposed to biomass burning organic aerosol (BBOA), composed of many compounds with wide ranges of chemical, physical, and optical properties, including volatility. The components of BBOA will partition onto the BC aggregates, and the resulting coatings will cause changes to the morphology and hygroscopicity of BC, which impact its interactions with radiation and clouds. Here, we investigate the effects of different volatility fractions of BBOA, representative of different ages of plumes with respect to dilution in the atmosphere, on BC restructuring. From timeseries of diameter growth factors for coated and coated-denuded BC particles, we determine that, as volatility decreases, more coating is necessary for the same amount of restructuring. We will discuss the results and their implications in the context of previous studies of BC restructuring. Broadly, our observations indicate that fresh wildfire plumes may have more potential to impact the morphology of BC at the wildland-urban interface.