HR: 11:10h
AN: A22C-04    [Abstracts]
TI: Nighttime Nitrate Radical Chemistry at Appledore Island, Maine during the 2004 International Consortium for Atmospheric Research on Transport and Transformation
AU: * Ambrose, J L
EM: jambrose@unh.edu
AF: Department of Chemistry, University of New Hampshire, Durham, NH 03824, United States
AU: * Ambrose, J L
EM: jambrose@unh.edu
AF: Climate Change Research Center, Institute for the Study of Earth Oceans and Space, University of New Hampshire, Durham, NH 03824, United States
AU: Mao, H
EM: hmao@gust.sr.unh.edu
AF: Climate Change Research Center, Institute for the Study of Earth Oceans and Space, University of New Hampshire, Durham, NH 03824, United States
AU: Mayne, H R
EM: howard.mayne@unh.edu
AF: Department of Chemistry, University of New Hampshire, Durham, NH 03824, United States
AU: Stutz, J
EM: jochen@atmos.ucla.edu
AF: Department of Atmospheric Sciences, University of California, Los Angeles, Los Angeles, CA 90095-1565, United States
AU: Talbot, R
EM: robert.talbot@unh.edu
AF: Climate Change Research Center, Institute for the Study of Earth Oceans and Space, University of New Hampshire, Durham, NH 03824, United States
AU: Sive, B C
EM: bcs@ccrc.sr.unh.edu
AF: Climate Change Research Center, Institute for the Study of Earth Oceans and Space, University of New Hampshire, Durham, NH 03824, United States
AB: Trace gases including nitrogen dioxide (NO₂), nitrate radical (NO₃), ozone (O₃), and a suite of volatile organic compounds (VOCs) were measured within the New England coastal marine boundary layer on Appledore Island (AI), Maine, USA as part of the International Consortium for Atmospheric Research on Transport and Transformation (ICARTT) field campaign. These measurements, together with local meteorological records and published kinetic data were used to investigate nighttime NO₃ chemistry at AI during the period of July 8 to 28, 2004. Among the VOCs, isoprene, monoterpenes and dimethylsulfide (DMS) were the dominant NO₃ reactants; on average, DMS accounted for 51 ± 34% of the total reactivity. For three case studies, NO₃ mixing ratios were calculated from measured parameters with resultant uncertainties of <30%. We indirectly determined that nighttime NO₃ and NO_x removal via N₂O₅ chemistry (gas-phase + heterogeneous) was on average 51 to 54% and 63 to 66% of the total respectively. Our analysis suggested that the minimum average NO₃ and NO_x removal via heterogeneous N₂O₅ chemistry was ~10% of the total; however, it is plausible that the latter pathway was often comparable to gas-phase removal of NO₃ and NO_x. Overall, 24 hr-averaged NO_x removal was ~11 ppbv, with nighttime chemical pathways contributing ~50%.
DE: 0322 Constituent sources and sinks
DE: 0345 Pollution: urban and regional (0305, 0478, 4251)
DE: 0365 Troposphere: composition and chemistry
SC: Atmospheric Sciences [A]
MN: 2007 Fall Meeting