AAAR 33rd Annual Conference
October 20 - October 24, 2014
Rosen Shingle Creek
Orlando, Florida, USA
Abstract View
Aged Biomass Burning Size Distributions from BORTAS 2011
KIMIKO SAKAMOTO, James Allan, Hugh Coe, Jonathan Taylor, Thomas Duck, Jeffrey Pierce, Colorado State University
Abstract Number: 7 Working Group: Biomass Burning Aerosol: From Emissions to Impacts
Abstract Biomass-burning aerosols contribute to aerosol radiative forcing on the climate system. The magnitude of this effect is partially determined by aerosol size distributions which are strong functions of source fire characteristics and in-plume microphysical processing. The uncertainties in biomass-burning emission number size-distributions in climate models lead to uncertainties in CCN concentrations and forcing estimates. The BORTAS-B measurement campaign collected data from boreal biomass-burning emissions over Eastern Canada in the summer of 2011 with the intention of adding to the body of observational datasets. We implement plume criteria to isolate the characteristic size-distribution of aged biomass-burning emissions (tilde 2 days) from fires in Northwestern Ontario. The composite size-distributions (Dpm = 232 nm, sigma = 1.7) are comparable to literature values of other aged plumes. The organic aerosol enhancement ratios (Delta OA/Delta CO) along the flight path show a strong, consistent correlations of (0.08-0.18) plusminus 0.01 across both flights that do not change with distance from the source, so no SOA production was detected within the aged plume. Finally, a Lagrangian microphysical model was used to determine an estimate of the freshly (tilde 1 hour) emitted size distribution and flux.