HR: 17:04h
AN: A24C-05    [Abstracts]
TI: Gas-to-Particle Conversion: Observations of Ammonium Nitrate Formation Above Houston
AU: * Nowak, J B
EM: John.Nowak@noaa.gov
AF: Cooperative Institute for Research in Environmental Sciences, University of Colorado, Boulder, CO 80309, United States
AU: * Nowak, J B
EM: John.Nowak@noaa.gov
AF: NOAA, Earth System Research Laboratory, Chemical Sciences Division, 325 Broadway, Boulder, CO 80305, United States
AU: Neuman, J A
EM: Andy.Neuman@noaa.gov
AF: Cooperative Institute for Research in Environmental Sciences, University of Colorado, Boulder, CO 80309, United States
AU: Neuman, J A
EM: Andy.Neuman@noaa.gov
AF: NOAA, Earth System Research Laboratory, Chemical Sciences Division, 325 Broadway, Boulder, CO 80305, United States
AU: Bahreini, R
EM: Roya.Bahreini@noaa.gov
AF: Cooperative Institute for Research in Environmental Sciences, University of Colorado, Boulder, CO 80309, United States
AU: Bahreini, R
EM: Roya.Bahreini@noaa.gov
AF: NOAA, Earth System Research Laboratory, Chemical Sciences Division, 325 Broadway, Boulder, CO 80305, United States
AU: Brock, C A
EM: Charles.A.Brock@noaa.gov
AF: NOAA, Earth System Research Laboratory, Chemical Sciences Division, 325 Broadway, Boulder, CO 80305, United States
AU: Middlebrook, A M
EM: Ann.M.Middlebrook@noaa.gov>
AF: NOAA, Earth System Research Laboratory, Chemical Sciences Division, 325 Broadway, Boulder, CO 80305, United States
AU: Wollny, A
EM: Adam.Wollny@noaa.gov
AF: Cooperative Institute for Research in Environmental Sciences, University of Colorado, Boulder, CO 80309, United States
AU: Wollny, A
EM: Adam.Wollny@noaa.gov
AF: NOAA, Earth System Research Laboratory, Chemical Sciences Division, 325 Broadway, Boulder, CO 80305, United States
AU: Holloway, J S
EM: John.S.Holloway@noaa.gov
AF: Cooperative Institute for Research in Environmental Sciences, University of Colorado, Boulder, CO 80309, United States
AU: Holloway, J S
EM: John.S.Holloway@noaa.gov
AF: NOAA, Earth System Research Laboratory, Chemical Sciences Division, 325 Broadway, Boulder, CO 80305, United States
AU: Peischl, J
EM: Jeff.Peischl@noaa.gov
AF: Cooperative Institute for Research in Environmental Sciences, University of Colorado, Boulder, CO 80309, United States
AU: Peischl, J
EM: Jeff.Peischl@noaa.gov
AF: NOAA, Earth System Research Laboratory, Chemical Sciences Division, 325 Broadway, Boulder, CO 80305, United States
AU: Ryerson, T B
EM: Thomas.B.Ryerson@noaa.gov
AF: NOAA, Earth System Research Laboratory, Chemical Sciences Division, 325 Broadway, Boulder, CO 80305, United States
AU: Fehsenfeld, F C
EM: Fred.C.Fehsenfeld@noaa.gov
AF: Cooperative Institute for Research in Environmental Sciences, University of Colorado, Boulder, CO 80309, United States
AU: Fehsenfeld, F C
EM: Fred.C.Fehsenfeld@noaa.gov
AF: NOAA, Earth System Research Laboratory, Chemical Sciences Division, 325 Broadway, Boulder, CO 80305, United States
AB: Ammonium nitrate aerosol is formed from the reaction of gas phase ammonia (NH₃) and nitric acid (HNO₃). Anthropogenic emissions of NH₃ and NOx (NO + NO₂), which is oxidized to form HNO₃, can react to form ammonium nitrate aerosol. Ammonium nitrate formation was observed from the NOAA WP3 aircraft over Houston during the TexAQS/GoMACCS 2006 study with fast-response measurements of NH₃, HNO₃, particle composition, and particle size distribution. Typically, NH₃ mixing ratios over the urban area ranged from 0.2 to 3 ppbv. However, several plumes with high NH₃ levels were sampled on different flights. NH₃ mixing ratios in these plumes ranged from 5 to over 50 ppbv. The high NH₃ mixing ratios shifted the equilibrium to conditions favorable for the formation of ammonium nitrate during the daytime. In these plumes, the NH₃ enhancement correlated with a decrease in HNO₃ mixing ratio and an increase in particulate NO₃^- concentration indicating ammonium nitrate formation. Particle size distribution and aerosol composition data will be analyzed to assess the quantitative agreement between the gas-phase and aerosol observations. Finally, the relationship between these plumes and the location of known NH₃ sources will be examined.
DE: 0300 ATMOSPHERIC COMPOSITION AND STRUCTURE
DE: 0305 Aerosols and particles (0345, 4801, 4906)
DE: 0345 Pollution: urban and regional (0305, 0478, 4251)
DE: 0365 Troposphere: composition and chemistry
DE: 0368 Troposphere: constituent transport and chemistry
SC: Atmospheric Sciences [A]
MN: 2007 Fall Meeting