AAAR 32nd Annual Conference
September 30 - October 4, 2013
Oregon Convention Center
Portland, Oregon, USA
Abstract View
Microphysical Simulation of Biomass-Burning Aerosol Size Distributions from BORTAS 2011
KIMIKO SAKAMOTO, James Allan, Hugh Coe, Jonathan Taylor, Thomas Duck, Jeffrey Pierce, Colorado State University
Abstract Number: 209 Working Group: Carbonaceous Aerosols in the Atmosphere
Abstract Biomass-burning aerosol size distributions are a function of combustion characteristics (e.g. fuel type, combustion efficiency) as well as near-source processing in the plume (e.g. coagulation, SOA formation and nucleation) that is not resolved by regional and global models. Thus, emitted size distributions vary in time in space, and emissions inventories of aerosol mass do not constrain aerosol and CCN number. These uncertainties in emissions number and size in global climate models leads to uncertainties in aerosol radiative forcings. We use aircraft-measured size distributions of biomass burning aerosol from the BORTAS field campaign to train a model of aerosol microphysics in biomass burning plumes. The microphysical simulations account for the aerosol processes occurring in a dense biomass-burning plume as it ages (coagulation, SOA formation/condensation, nucleation, entrainment, diffusion and plume dispersion). The model is initialized with emissions taken from GFED3 for July 19th, 2011 over Western Ontario (52.25 N, 90.75 W). We use the measurements to estimate the size distributions, SOA formation and nucleation rates by optimizing the model inputs to provide matching size distributions to the measurements. Future work will involve applying these techniques to other datasets of biomass-burning aerosol and creating parameterizations of biomass-burning number and size for regional and global models.