HR: 17:24h
AN: A14A-07    [Abstracts]
TI: Remote Sensing of Glyoxal as a New Atmospheric Tracer for VOC Chemistry and Secondary Organic Aerosol Formation in the Mexico City Metropolitan Area
AU: * Volkamer, R
EM: rainer@mit.edu
AF: Departments of Earth, Atmospheric and Planetary Sciences and of Chemistry, Massachusetts Institute of Technology, 77 Massachusetts Ave, Cambridge, MA 02139 United States
AU: Molina, L T
AF: Departments of Earth, Atmospheric and Planetary Sciences and of Chemistry, Massachusetts Institute of Technology, 77 Massachusetts Ave, Cambridge, MA 02139 United States
AU: Molina, M J
AF: Departments of Earth, Atmospheric and Planetary Sciences and of Chemistry, Massachusetts Institute of Technology, 77 Massachusetts Ave, Cambridge, MA 02139 United States
AU: Shirley, T
AF: Pennsylvania State University, Department of Meteorology, 503 Walker Bldg., University Park, PA 16802 United States
AU: Lesher, R
AF: Pennsylvania State University, Department of Meteorology, 503 Walker Bldg., University Park, PA 16802 United States
AU: Brune, W
AF: Pennsylvania State University, Department of Meteorology, 503 Walker Bldg., University Park, PA 16802 United States
AU: Dzepina, K
AF: University of Colorado-Boulder, Department of Chemistry & Biochemistry; and CIRES, UCB 216, Boulder, CO 80309 United States
AU: Jimenez, J
AF: University of Colorado-Boulder, Department of Chemistry & Biochemistry; and CIRES, UCB 216, Boulder, CO 80309 United States
AB: Air pollution in the Mexico City Metropolitan Area (MCMA) is intimately linked with the photochemical transformation of primary pollutants like VOC (volatile organic compounds) and NOx, which gives rise to the formation of secondary pollutants such as ozone and secondary organic aerosol (SOA) and their associated adverse effects on human health. As part of the field campaign held in the MCMA in April/May 2003, state-of-the-art measurement techniques including open-path Differential Optical Absorption Spectroscopy (DOAS), spectroradiometry, Aerosol Mass Spectrometry (AMS) and Laser Induced Fluorescence (LIF) were located at the National Center for Environmental Research and Training (CENICA) in Mexico City to characterize the gas-phase and aerosol-phase composition of relevance to the formation of ozone and SOA. A first-ever spectroscopic detection of glyoxal (DOAS) in the atmosphere is described. Glyoxal is shown to be a very useful new photochemical tracer for the chemistry of VOC. The time-resolved glyoxal measurements reveal a very efficient VOC oxidation process during morning hours, which is found to be relevant for overall smog formation later in the day. In combination with measurements of the radical precursor substances HONO, HCHO, ozone (DOAS), their respective J-values (spectroradiometry), OH- and HO2-radical concentrations (LIF), speciated aromatic hydrocarbons (DOAS) and chemical composition of the aerosol phase (AMS), the glyoxal data enables assessment of the role of VOC oxidation in the formation of secondary pollutants in the gas- and aerosol-phase by placing a lower limit on the extend of VOC turnover.
DE: 0305 Aerosols and particles (0345, 4801)
DE: 0317 Chemical kinetic and photochemical properties
DE: 0345 Pollution--urban and regional (0305)
DE: 0365 Troposphere--composition and chemistry
DE: 0394 Instruments and techniques
SC: Atmospheric Sciences [A]
MN: 2004 AGU Fall Meeting