HR: 0800h
AN: A11A-0001    [Abstracts]
TI: Hydrocarbon Measurements during the MCMA2003 Field Experiment: Intercomparison and Analysis
AU: * Jobson, B T
EM: tom.jobson@pnl.gov
AF: Pacific Northwest National Laboratory, PO Box 999, Richland, WA 99352 United States
AU: Alexander, M L
EM: michael.alexander@pnl.gov
AF: Pacific Northwest National Laboratory, PO Box 999, Richland, WA 99352 United States
AU: Prazeller, P
EM: peter.prazeller@rdls.nestle.com
AF: Pacific Northwest National Laboratory, PO Box 999, Richland, WA 99352 United States
AU: Berkowitz, C M
EM: carl.berkowitz@pnl.gov
AF: Pacific Northwest National Laboratory, PO Box 999, Richland, WA 99352 United States
AU: Volkamer, R
EM: rainer@mit.edu
AF: Massachusetts Institute of Technology, 77 Massachusetts Ave., Cambridge, MA 02139 United States
AU: Molina, L T
EM: ltmolina@mit.edu
AF: Massachusetts Institute of Technology, 77 Massachusetts Ave., Cambridge, MA 02139 United States
AU: Westberg, H
EM: westberg@mail.wsu.edu
AF: Washington State University, Dept. Civil and Environmental Engineering Sloan Hall, Spokane Street, Pullman, WA 99164 United States
AU: Lamb, B
EM: blamb@wsu.edu
AF: Washington State University, Dept. Civil and Environmental Engineering Sloan Hall, Spokane Street, Pullman, WA 99164 United States
AU: Velasco, E
EM: he_velasco@wsu.edu
AF: Washington State University, Dept. Civil and Environmental Engineering Sloan Hall, Spokane Street, Pullman, WA 99164 United States
AU: Allwine, E
EM: allwineg@wsu.edu
AF: Washington State University, Dept. Civil and Environmental Engineering Sloan Hall, Spokane Street, Pullman, WA 99164 United States
AB: To better understand the photochemical production of ozone and secondary organic aerosol in Mexico City, volatile hydrocarbon measurements were made from the roof top of the Mexican National Research and Training Center (CENICA) in Iztapalapa during the Mexico City Metropolitan Area field experiment in April 2003. Three distinct techniques were used: on-line chemical ionization using a proton transfer reaction mass spectrometer (PTR-MS), long path measurements using a UV differential optical absorption spectrometer (DOAS), and gas chromatography - flame ionization analysis (GC-FID) of canisters samples. The PTR-MS provided high time resolution data of several aromatic and oxygenated species, and monitored masses corresponding to volatile aromatic oxidation products. The DOAS instrument likewise made high time resolution measurements of a several aromatic and oxygenated species, while the canister data reported C2-C10 hydrocarbons. An intercomparison of these techniques for several species measured in common is reported, including a comparison of standards used for calibration. Results show a good agreement between the PTR-MS and UV DOAS calibrations for several aromatic species. Differences in ambient data were therefore determined to be due to significant concentration gradients over the path length of the DOAS. The comparison between PTR-MS and GC-FID data indicate that fragmentation of higher aromatics likely caused the PTR to overestimate benzene mixing ratios. The ambient aromatic data displayed significant diel variability. Oxygenated species displayed different temporal variability patterns, indicating the importance of photochemical sources in the afternoon. These temporal patterns and hydrocarbon ratios were compared to those observed in US cities to highlight differences between Mexico City hydrocarbon distribution and reactivity.
DE: 0345 Pollution--urban and regional (0305)
DE: 0365 Troposphere--composition and chemistry
DE: 0368 Troposphere--constituent transport and chemistry
DE: 0394 Instruments and techniques
SC: Atmospheric Sciences [A]
MN: 2004 AGU Fall Meeting