AAAR 33rd Annual Conference
October 20 - October 24, 2014
Rosen Shingle Creek
Orlando, Florida, USA
Abstract View
Relative Importance of Black vs. Brown Carbon Absorption in Biomass Burning Plumes
SHANE MURPHY, Rudra Pokhrel, Eric Beamesderfer, Daniel Lack, Nick Wagner, Justin Langridge, Daniel Murphy, University of Wyoming
Abstract Number: 488 Working Group: Carbonaceous Aerosols in the Atmosphere
Abstract Biomass burning represents one of the largest global sources of absorbing aerosol. Despite the importance of biomass burning emissions on the Earth’s radiative balance, there remains significant uncertainty about the optical properties of emitted particles. Of particular interest is the impact of lensing on black carbon absorption and the impact of brown carbon. This presentation describes results from the Fire Lab at Missoula Experiment-4 (FLAME-4), which occurred in October 2012. Multi-channel photoacoustic (PAS) and Cavity Ringdown (CRDS) spectrometers were used to measure absorption, extinction, and absorption enhancement of aerosols particles produced from a wide range of globally relevant biomass fuels. Measurements were made at 405, 532, and 660 nm with duplicate channels at 405 and 660 measuring denuded particles, allowing for direct observation of the enhancement of absorption by black carbon particles caused by clear and brown organic coatings. Fuels were chosen based on their contribution to global wildfire and cooking emissions. Data from fresh biomass burning emissions and from emission photochemically oxidized in a smog chamber will be presented. The impact of photochemical aging on the absorption and single scattering albedo (SSA) of organic aerosols produced by biomass burning will be discussed. The SSA and absorption angstrom exponent (AAE) of different biomass fuels will be explored and the relative importance of black and brown carbon emitted from different biomass fuels will be assessed.