AAAR 31st Annual Conference
October 8-12, 2012
Hyatt Regency Minneapolis
Minneapolis, Minnesota, USA
Abstract View
Cloud Condensation Nuclei Activity and Hygroscopicity of In-situ Biomass Burning Aerosol
TERRY LATHEM, Bruce Anderson, Andreas Beyersdorf, Lee Thornhill, Edward Winstead, Joe Shaw, Michael Thomas, Glenn Shaw, Athanasios Nenes, Georgia Institute of Technology
Abstract Number: 191 Working Group: Aerosols, Clouds, and Climate
Abstract Biomass burning (BB) is a major source of aerosol with both natural and anthropogenic origins. Emissions are expected to increase in a warming climate and the ability of smoke to be transported across the globe increases the impacts on the earth system, especially the Arctic. The overall hygroscopicity and aging characteristics of BB aerosol is not well quantified, although many studies suggest BB aerosol is efficient cloud condensation nuclei (CCN). Recent laboratory studies of controlled single-fuel burns reveal that the hygroscopic properties of primary smoke particles can be highly variable, depending on both the fuel source and age, with decreasing variability as samples age and become more oxidized. However, BB aerosol in the atmosphere can be a complex mixture of multiple fuel types, undergoing potential rapid aging and mixing with background aerosol, so it is also important to quantify properties of BB particles in the ambient environment.
In this study, we investigate the hygroscopic properties of in-situ BB aerosol generated from active boreal forest fires in the regions of Montana and Canada. Extensive airborne data of boreal forest fire smoke was collected during the 2008 NASA ARCTAS campaign, and we present a detailed characterization of the physical, chemical, and hygroscopic properties of the aerosol collected over Canada. Additional in-situ smoke data was collected at a ground site at Montana State University during the summer of 2009. We find that BB aerosol is efficient CCN, despite high organic content, because a significant fraction of the organic material is water soluble and hygroscopic. CCN predictions, including AMS chemistry and measured water soluble organic carbon, are in excellent agreement with observations, matching within +/- 25%. We also explore how aging influences particle hygroscopicity and investigate observations of new particle formation within BB plumes.