Size, Time, and Composition-Resolved Aerosol Measurements in Mexico City During the MCMA-2003 Field Campaign: The Organic Component

HR: 0800h
AN: A11A-0018 [Abstracts]
TI: Size, Time, and Composition-Resolved Aerosol Measurements in Mexico City During the MCMA-2003 Field Campaign: The Organic Component
AU: * Dzepina, K
EM: katja.dzepina@colorado.edu
AF: University of Colorado at Boulder, Dept. of Chemistry & Biochemistry; and CIRES UCB 216, Boulder, CO 80309 United States
AU: Salcedo, D
EM: dara@ciq.uaem.mx
AF: Universidad Aut¢noma del Estado de Morelos, Av. Universidad #1001, Cuernavaca Morelos, 62210 Mexico
AU: Zhang, Q
EM: zhangq@cires.colorado.edu
AF: University of Colorado at Boulder, Dept. of Chemistry & Biochemistry; and CIRES UCB 216, Boulder, CO 80309 United States
AU: Dunn, M
EM: mattdunn@ucar.edu
AF: University of Colorado at Boulder, Dept. of Chemistry & Biochemistry; and CIRES UCB 216, Boulder, CO 80309 United States
AU: Dunn, M
EM: mattdunn@ucar.edu
AF: NCAR, ACD, PO Box 3000, Boulder, CO 80305-3000 United States
AU: DeCarlo, P
EM: peter.decarlo@colorado.edu
AF: University of Colorado at Boulder, Dept. of Chemistry & Biochemistry; and CIRES UCB 216, Boulder, CO 80309 United States
AU: Huffman, A
EM: alex.huffman@colorado.edu
AF: University of Colorado at Boulder, Dept. of Chemistry & Biochemistry; and CIRES UCB 216, Boulder, CO 80309 United States
AU: Jimenez, J
EM: jose.jimenez@colorado.edu
AF: University of Colorado at Boulder, Dept. of Chemistry & Biochemistry; and CIRES UCB 216, Boulder, CO 80309 United States
AU: Onasch, T
EM: onasch@aerodyne.com
AF: ARI, 45 Manning Road, Billerica, MA 01821-3976 United States
AU: Mortimer, P
EM: mortimer@aerodyne.com
AF: ARI, 45 Manning Road, Billerica, MA 01821-3976 United States
AU: Jayne, J
EM: jayne@aerodyne.com
AF: ARI, 45 Manning Road, Billerica, MA 01821-3976 United States
AU: Canagaratna, M
EM: mrcana@aerodyne.com
AF: ARI, 45 Manning Road, Billerica, MA 01821-3976 United States
AU: Worsnop, D
EM: worsnop@aerodyne.com
AF: ARI, 45 Manning Road, Billerica, MA 01821-3976 United States
AU: Gaffney, J
EM: gaffney@anl.gov
AF: ANL, Environmental Research Division Bldg. 203/ER , Argonne, IL 60439 United States
AU: Marley, N
EM:
AF: ANL, Environmental Research Division Bldg. 203/ER , Argonne, IL 60439 United States
AU: Volkamer, R
EM: rainer@mit.edu
AF: MIT, 77 Massachusetts Av., Cambridge, MA 02139 United States
AU: de Foy, B
EM: foy@mit.edu
AF: MIT, 77 Massachusetts Av., Cambridge, MA 02139 United States
AU: Frey, S
EM: lidar@mit.edu
AF: MIT, 77 Massachusetts Av., Cambridge, MA 02139 United States
AU: Johnson, K
EM: kirstenj@mit.edu
AF: MIT, 77 Massachusetts Av., Cambridge, MA 02139 United States
AU: Zuberi, B
EM: bilal@alum.mit.edu
AF: MIT, 77 Massachusetts Av., Cambridge, MA 02139 United States
AU: Zuberi, B
EM: bilal@alum.mit.edu
AF: GEO2 Technologies, 770 Boylston St. 9A, Boston, MA 02199 United States
AU: Molina, L T
EM: ltmolina@mit.edu
AF: MIT, 77 Massachusetts Av., Cambridge, MA 02139 United States
AU: Molina, M J
EM: mmolina@mit.edu
AF: MIT, 77 Massachusetts Av., Cambridge, MA 02139 United States
AU: Bernab‚, R
EM: bcar@xanum.uam.mx
AF: CENICA and INE, Av. San Rafael Atlixco No. 186, Col. Vicentina, Iztapalapa, M‚xico D.F., C.P. 09340 Mexico
AU: M rquez, C
EM: bcar@xanum.uam.mx
AF: CENICA and INE, Av. San Rafael Atlixco No. 186, Col. Vicentina, Iztapalapa, M‚xico D.F., C.P. 09340 Mexico
AU: Blanco, S
AF: CENICA and INE, Av. San Rafael Atlixco No. 186, Col. Vicentina, Iztapalapa, M‚xico D.F., C.P. 09340 Mexico
AU: Angeles, F
AF: CENICA and INE, Av. San Rafael Atlixco No. 186, Col. Vicentina, Iztapalapa, M‚xico D.F., C.P. 09340 Mexico
AU: Cardenas, B
EM: bcar@xanum.uam.mx
AF: CENICA and INE, Av. San Rafael Atlixco No. 186, Col. Vicentina, Iztapalapa, M‚xico D.F., C.P. 09340 Mexico
AU: Shirley, T
EM: trs161@psu.edu
AF: Pennsylvania State University, Department of Meteorology 503 Walker Bldg., University Park, PA 16802 United States
AU: Lesher, R
EM: blesher@psu.edu
AF: Pennsylvania State University, Department of Meteorology 503 Walker Bldg., University Park, PA 16802 United States
AU: Brune, W
EM: brune@essc.psu.edu
AF: Pennsylvania State University, Department of Meteorology 503 Walker Bldg., University Park, PA 16802 United States
AU: Smith, J
EM: jimsmith@ucar.edu
AF: NCAR, ACD, PO Box 3000, Boulder, CO 80305-3000 United States
AB: An Aerodyne Aerosol Mass Spectrometer (AMS) was deployed to the CENICA Supersite during the Mexico City Metropolitan Area (MCMA-2003) field study from March 29 - May 4, 2003. Organic aerosols dominate the NR-PM$_{1}$ aerosol concentrations in Mexico City during MCMA-2003, and are the focus of this presentation (inorganic species: Salcedo et al., this conference). We have applied a procedure based on internal AMS tracers (Zhang et al., this conference) to estimate the concentrations and size distributions of primary and oxygenated organic aerosols (POA and OOA respectively). OOA encompasses secondary organic aerosol (SOA) as well as oxidized POA. This method is based on iterative principal component analysis with a custom method that uses AMS {\it m/z} 57 and {\it m/z}44 as initial time series for POA and OOA respectively. During MCMA-2003 POA shows good correlation with primary combustion emissions (such as CO, BC, and NO$_{x}$), and SOA shows correlation with photochemical products (such as O$_{3}$ and glyoxal). Our results show that organic aerosols during MCMA-2003 were comprised of $\sim$35% POA, and $\sim$65% OOA. Intense SOA formation was observed many of the days, which is consistent with the high levels of aerosol precursors (aromatics), UV radiation, and of radicals (OH, HO$_{2}$) measured by other researchers. OOA in Mexico City is likely dominated by SOA from the oxidation of aromatic species. The aerosol size distribution was often bimodal, with a smaller mode, $\sim$100 nm in {\it d$_{va}$},(i.e., aerodynamic diameter in free molecular regime) characteristic of traffic emissions, and a larger accumulation mode ($\sim$500 nm {\it d$_{va}$}) dominated by photochemical products. The ultrafine ($<$ 100 nm) composition is analyzed with collocated measurements from a nano-SMPS and the AMS. Traffic-related POA dominates the ultrafine mode every morning during rush hour. Ultrafine particles in the afternoon contain both sulfate and organics (both POA and SOA). A nucleation event was observed inside the city when the aerosol surface area was relatively low.
DE: 0305 Aerosols and particles (0345, 4801)
SC: Atmospheric Sciences [A]
MN: 2004 AGU Fall Meeting