Observations of Volatile Organic Compounds in Biomass Burning Plumes During POLARCAT/ARCTAS

During the POLARCAT/ARCTAS field study in the spring and summer 2008, the NASA DC-8 sampled a number of biomass burning fire plumes of varying ages and origins in Alaska and the Canadian Arctic, in California, and in the Boreal Region of Central Canada. Several instruments aboard the DC-8 made observations of volatile organic compounds (VOCs) during the study, including the Trace Organic Gas Analyzer (TOGA), a Proton-transfer mass spectrometer (PTR-MS), Chemical ionization mass spectrometers (CIMS), and whole-air canisters analyzed by laboratory GC analysis. Using the TOGA data from fire plume encounters with observations of carbon monoxide, we determined the enhancement ratio (ER), ΔVOC/ΔCO, for selected non-methane hydrocarbons and other VOCs for individual fire plumes. For comparison, we also determined the plume-specific ERs for these and a few other compounds from the other VOC-measurement techniques onboard the DC-8. Although ERs for some VOCs vary significantly between plumes, there is generally good agreement between the instruments for plume-specific ERs. Notable exceptions to this are acetonitrile ERs measured in the California region, and methyl ethyl ketone ERs measured in the California and Canadian Boreal Regions. We will explore the dependence of ERs on biomass burning source and location, plume age (processing) and fire combustion efficiency, and compare these to previously published findings.