AAAR 33rd Annual Conference
October 20 - October 24, 2014
Rosen Shingle Creek
Orlando, Florida, USA
Abstract View
Transmission Electron Microscopy Analysis of Biomass-Burning Aerosol Particles during BBOP Campaign 2013
KOUJI ADACHI, Arthur J. Sedlacek, Lawrence Kleinman, Duli Chand, Peter Buseck, Meteorological Research Institute
Abstract Number: 76 Working Group: Biomass Burning Aerosol: From Emissions to Impacts
Abstract From July to October 2013, the Department of Energy’s Atmospheric Radiation Monitoring (ARM) program sponsored an aircraft-based field campaign (Biomass Burning Observation Project (BBOP)) to study the near-field evolution of particulate emissions from biomass burning. Aerosol particles from wildfires in the Western US (Idaho, Oregon, and Washington) and from agricultural burns in the Mississippi Embayment (Arkansas) were sampled. Transmission electron microscopy (TEM) was used to analyze the mixing states, shapes, and compositions of aerosol particles within the smoke at differing plume ages. Here, we focus on tar ball particles, which are a subset of organic aerosol that is characterized by a spherical shape and amorphous composition. Tar balls are presumed to be brown-carbon (BrC) particles that can contribute to light absorption in the atmosphere. Since tar balls can be identified from their spherical shape using electron microscopy, an investigation of their detailed compositions, formation processes, and occurrence in the atmosphere, all of which are largely unknown, can be conducted. In this campaign, we found that tar balls primarily originated from wildfires. They are most abundant in relatively aged plumes (>several hours from emission). On the flight conducted on July 30, organic aerosol particles formed tar balls as the smoke plume aged. Their shapes, sizes, and compositions were similar to those from Mexico measured during the MILAGRO campaign (2006), but their number fractions were more abundant in the current study. In this presentation, we will discuss their occurrence, formation, and implications of their climate effects from the results of TEM and other on-line instruments.