AAAR 36th Annual Conference October 16 - October 20, 2017 Raleigh Convention Center Raleigh, North Carolina, USA
Abstract View
Evolution of Optical Properties of Biomass Burning-Derived Particles
CHRISTOPHER CAPPA, Christopher Lim, David Hagan, Jesse Kroll, Matthew Coggon, Abigail Koss, Timothy Onasch, University of California, Davis
Abstract Number: 637 Working Group: Aerosol Chemistry
Abstract Biomass burning constitutes a substantial source of particulate matter to the atmosphere. Black carbon is a strongly absorbing component of particulate matter and can be emitted in large quantities from biomass fires. Biomass fires also emit organic aerosol (OA) particles. The light absorption properties of emitted OA is dependent upon the conditions of the fire at the time of emission and the fuel type. These emitted particles undergo chemical transformations post-emission, which alter their chemical and optical properties. There are few studies that have addressed how photochemical processing impacts the optical properties of biomass burning-derived particles. Here, we report on measurements of the optical evolution of freshly emitted biomass-derived particles and gases from a variety of sources as they are subject to photochemical processing. The measurements were made as part of the Fire Influences on Regional and Global Environments Experiment (FIREX) campaign at the Missoula Fire Sciences Laboratory. Using a novel oxidation chamber, continuous photochemical ageing of particles and gases up to many days of equivalent aging is carried out. We examine the extent to which photochemical processing alters properties such as the wavelength-dependent single scattering albedo and mass absorption coefficient. We discern differences in how oxidation impacts black carbon absorption versus absorption by OA, and how this depends on particle mixing state. We consider how the optical evolution depends on the fire conditions (e.g. flaming vs. smoldering) and fuel type.