Longer-range Transport and Longer-term Aging of Biomass Burning Influenced Atmospheric Organic Aerosol

RACHEL O'BRIEN, Janie (Yeaseul) Kim, Corin Tyler, Emily Costa, Xu He, Yao Xiao, Andrew Ault, Manjula Canagaratna, Mitchell Alton, Benjamin A. Nault, Christopher Cappa, Cassandra Gaston, Ann M. Dillner, Haley Royer, Alyson Allen, Edmund Blades, Rebecca Chewitt-Lucas, University of Michigan

     Abstract Number: 225
     Working Group: Coast to Coast Campaigns on Aerosols, Clouds, Chemistry, and Air Quality

Abstract
Brown carbon (BrC) in aerosol particles and cloud droplets can contribute to climate warming by absorbing solar radiation in the visible region of the solar spectrum. Large uncertainties remain in our parameterization of this warming, in part due to gaps in our knowledge of the atmospheric lifetimes of the light absorbing molecules in the mixtures. An important removal pathway includes chemical transformations that fragment the chromophore, thus removing its ability to absorb visible light. However, the photochemical loss rates measured in the laboratory are much shorter than what is observed in ambient measurements. There are also different amounts of photo-recalcitrant BrC, which is a fraction of the mixture that does not rapidly bleach. An important BrC source in the atmosphere is biomass burning and the overall photochemical decay rates for these emissions are important to quantify to improve our parameterizations for their radiative effects. In this talk, I will be combining results from photolysis studies in our lab, along with results of biomass burning influenced samples collected during AEROMMA that came from the Canadian wildfires and collected at Barbados that came from African wildfires.