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Title: An improved representation of fire non-methane organic gases (NMOGs) in models: emissions to reactivity
Abstract. Fires emit a substantial amount of non-methane organic gases (NMOGs), theatmospheric oxidation of which can contribute to ozone and secondaryparticulate matter formation. However, the abundance and reactivity of thesefire NMOGs are uncertain and historically not well constrained. In thiswork, we expand the representation of fire NMOGs in a global chemicaltransport model, GEOS-Chem. We update emission factors to Andreae (2019) andthe chemical mechanism to include recent aromatic and ethene and ethyne modelimprovements(Bateset al., 2021; Kwon et al., 2021). We expand the representation of NMOGs byadding lumped furans to the model (including their fire emission andoxidation chemistry) and by adding fire emissions of nine species alreadyincluded in the model, prioritized for their reactivity using data from the Fire Influence on Regional to Global Environments (FIREX) laboratory studies. Based on quantified emissions factors, we estimatethat our improved representation captures 72 % of emitted, identified NMOGcarbon mass and 49 % of OH reactivity from savanna and temperate forestfires, a substantial increase from the standard model (49 % of mass,28 % of OH reactivity). We evaluate fire NMOGs in our model withobservations from the Amazon Tall Tower Observatory (ATTO) in Brazil, Fire Influence on Regional to Global Environments and Air Quality (FIREX-AQ) and DC3 in the US, and Arctic Research of the Composition of theTroposphere from Aircraft and Satellites (ARCTAS) in boreal Canada. We show that NMOGs,including furan, are well simulated in the eastern US with someunderestimates in the western US and that adding fire emissions improves ourability to simulate ethene in boreal Canada. We estimate that fires provide15 % of annual mean simulated surface OH reactivity globally, as well as morethan 75 % over fire source regions. Over continental regions about half ofthis simulated fire reactivity comes from NMOG species. We find that furansand ethene are important globally for reactivity, while phenol is moreimportant at a local level in the boreal regions. This is the first globalestimate of the impact of fire on atmospheric reactivity.  more » « less
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Journal Name:
Atmospheric Chemistry and Physics
Page Range / eLocation ID:
12093 to 12111
Medium: X
Sponsoring Org:
National Science Foundation
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