AAAR 36th Annual Conference October 16 - October 20, 2017 Raleigh Convention Center Raleigh, North Carolina, USA
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Modeling the Formation of Secondary Organic Aerosol Precursors from Isoprene
KELVIN BATES, John Seinfeld, Paul Wennberg, California Institute of Technology
Abstract Number: 661 Working Group: Aerosol Chemistry
Abstract Isoprene, a volatile hydrocarbon emitted by plants, represents the single most abundant source of non-methane organic carbon to the atmosphere. After its rapid oxidation by OH radicals in the troposphere, isoprene may follow any of a number of complex reaction mechanisms to form more highly functionalized products, depending in large part on the relative abundance of reactive radicals such as HO2 and NO; some of these products can be sufficiently water-soluble, non-volatile, and/or reactive to partition into atmospheric particles and contribute to the creation of secondary organic aerosol (SOA). In this work, a comprehensive mechanism of isoprene oxidation is incorporated into GEOS-Chem, a global chemical transport model, to investigate the formation of SOA precursors such as isoprene epoxydiols (IEPOX), methacryloyl peroxynitrate (MPAN), and tetrafunctionalized species including dihydroxy-dihydroperoxides and dihydroxy-nitrates. We explore the spatial and temporal distribution of these products, and find that upwards of 180 Tg y-1 of IEPOX, 30 Tg y-1 of MPAN, and 40 Tg y-1 of tetrafunctional species are produced in the atmosphere, representing a significant source of SOA mass globally. We further investigate various methods of parameterizing SOA formation from these precursors for incorporation into models.