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Mixing ratios of a large number of nonmethane organic compounds (NMOCs) wereobserved by the Trace Organic Gas Analyzer (TOGA) on board the NASA DC-8 aspart of the Arctic Research of the Composition of the Troposphere fromAircraft and Satellites (ARCTAS) field campaign. Many of these NMOCs wereobserved concurrently by one or both of two other NMOC measurementtechniques on board the DC-8: proton-transfer-reaction mass spectrometry(PTR-MS) and whole air canister sampling (WAS). A comparison of thesemeasurements to the data from TOGA indicates good agreement for the majorityof co-measured NMOCs. The ARCTAS study, which included both spring andsummer deployments, provided opportunities to sample a large number ofbiomass burning (BB) plumes with origins in Asia, California and centralCanada, ranging from very recent emissions to plumes aged one week or more.For this analysis, BB smoke interceptions were grouped by flight, sourceregion and, in some cases, time of day, generating 40 identified BB plumesfor analysis. Normalized excess mixing ratios (NEMRs) to CO were determinedfor each of the 40 plumes for up to 19 different NMOCs or NMOC groups.Although the majority of observed NEMRs for individual NMOCs or NMOC groupswere in agreement with previously-reported values, the observed NEMRs to COfor ethanol, a rarely quantified gas-phase trace gas, ranged from valuessimilar to those previously reported, to up to an order of magnitudegreater. Notably, though variable between plumes, observed NEMRs ofindividual light alkanes are highly correlated within BB emissions,independent of estimated plume ages. BB emissions of oxygenated NMOC werealso found to be often well-correlated. Using the NCAR Master Mechanismchemical box model initialized with concentrations based on two observedscenarios, fresh Canadian BB and fresh Californian BB, decreases arepredicted for the low molecular weight carbonyls (i.e. formaldehyde,acetaldehyde, acetone and methyl ethyl ketone, MEK) and alcohols (i.e.methanol and ethanol) as the plumes evolve in time, i.e. the production ofthese compounds is less than the chemical loss. Comparisons of the modeledNEMRs to the observed NEMRs from BB plumes estimated to be three days in ageor less indicate overall good agreement

Observations of nonmethane organic compounds during ARCTAS − Part 1: Biomass burning emissions and plume enhancements