Comparison of chemical characteristics of 495 biomass burning plumes intercepted by the NASA DC-8 aircraft during the ARCTAS/CARB-2008 field campaign

Abstract

Abstract. This paper compares measurements of gaseous and particulate emissions from a wide range of biomassburning 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.Correspondence to: A. Hecobian (arsineh@gatech.edu)The comparison of NEMR values showed that CH 4 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 NO x 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.

Properties and evolution of biomass burning organic aerosol from Canadian boreal forest fires

“…Mean f 44 for B626, which comprised the only measurements of fresh OA during BOR-TAS, was lower than all other flights at 0.086 ± 0.014, with mean values for B621-B624 ranging from 0.104 to 0.139. This trend between the near and far-field is consistent with observations of boreal forest fire plumes during ARCTAS, where f 44 was shown to increase as a function of plume transport time (Cubision et al, 2011;Hecobian et al, 2011). f 60 was also shown to decrease concurrently with increasing f 44 during ARCTAS, as a result of the oxidation of primary levoglucosan-type species with aging.…”

Spectral absorption of biomass burning aerosol determined from retrieved single scattering albedo during ARCTAS

“…A higher O/C ratio together with a higher OS C determined for the 17 April plume, suggest the 17 April OA is more oxidized than the 29 June OA. During ARCTAS, Hecobian et al (2011) and Cubison et al (2011) found little evidence for net SOA formation in the Canadian biomass burning plumes encountered by the DC-8, although some SOA formation may have been compensated by POA evaporation. The effect of SOA formation during transport of the Siberian plume is unconstrained by the ARCTAS data, but by analogy with the Canadian plumes it is likely to have been minor.…”

Airborne observations of trace gases over boreal Canada during BORTAS: campaign climatology, air mass analysis and enhancement ratios

“…For this reason, the ER for short-lived species should only be calculated using measurements in the freshest possible fire plumes. In aged plumes the regression slope is usually known as a normalised excess mixing ratio (NEMR) or enhancement ratio instead Hecobian et al, 2011;Akagi et al, 2011Akagi et al, , 2012Le Breton et al, 2013;Yokelson et al, 2013).…”