Comparison of chemical characteristics of 495 biomass burning plumes intercepted by the NASA DC-8 aircraft during the ARCTAS/CARB-2008 field campaign
1School of Earth and Atmospheric Sciences, Georgia Institute of Technology, Atlanta, GA, USA
2Department of Chemistry and Biochemistry and Cooperative Institute for Research in Environmental Sciences (CIRES), University of Colorado, Boulder, CO, USA
3NASA/Langley Research Center, Hampton, VA, USA
4Institute for Ion Physics and Applied Physics, Innsbruck University, Innsbruck, Austria
5National Center for Atmospheric Research, Boulder, CO, USA
6Atmospheric Chemistry and Environmental Engineering, California Institute of Technology, Pasadena, CA, USA
7Institute for Atmospheric and Environmental Sciences, Johann Wolfgang Goethe University Frankfurt am Main, 60438 Frankfurt am Main, Germany
*now at: Department of Atmospheric Science, Colorado State University, Fort Collins, CO, USA
**now at: Center for Atmospheric Particle Studies, Carnegie Mellon University, Pittsburgh, PA, USA
Abstract. This paper compares measurements of gaseous and particulate emissions from a wide range of biomass-burning plumes intercepted by the NASA DC-8 research aircraft during the three phases of the ARCTAS-2008 experiment: ARCTAS-A, based out of Fairbanks, Alaska, USA (3 April to 19 April 2008); ARCTAS-B based out of Cold Lake, Alberta, Canada (29 June to 13 July 2008); and ARCTAS-CARB, based out of Palmdale, California, USA (18 June to 24 June 2008). Approximately 500 smoke plumes from biomass burning emissions that varied in age from minutes to days were segregated by fire source region and urban emission influences. The normalized excess mixing ratios (NEMR) of gaseous (carbon dioxide, acetonitrile, hydrogen cyanide, toluene, benzene, methane, oxides of nitrogen and ozone) and fine aerosol particulate components (nitrate, sulfate, ammonium, chloride, organic aerosols and water soluble organic carbon) of these plumes were compared. A detailed statistical analysis of the different plume categories for different gaseous and aerosol species is presented in this paper.
The comparison of NEMR values showed that CH4 concentrations were higher in air-masses that were influenced by urban emissions. Fresh biomass burning plumes mixed with urban emissions showed a higher degree of oxidative processing in comparison with fresh biomass burning only plumes. This was evident in higher concentrations of inorganic aerosol components such as sulfate, nitrate and ammonium, but not reflected in the organic components. Lower NOx NEMRs combined with high sulfate, nitrate and ammonium NEMRs in aerosols of plumes subject to long-range transport, when comparing all plume categories, provided evidence of advanced processing of these plumes.