HR: 12:05h
AN: A52A-08    [Abstracts]
TI: Development of an explicit mechanistic model for isoprene oxidation, assessed by atmospheric chamber experiments
AU: * Paulot, F
EM: paulot@caltech.edu
AF: California Institute of Technology, 1200 E. California Blvd, Pasadena, CA 91125, United States
AU: Wennberg, P O
EM: wennberg@caltech.edu
AF: California Institute of Technology, 1200 E. California Blvd, Pasadena, CA 91125, United States
AU: Crounse, J D
EM: crounjd@caltech.edu
AF: California Institute of Technology, 1200 E. California Blvd, Pasadena, CA 91125, United States
AU: Seinfeld, J H
EM: seinfeld@caltech.edu
AF: California Institute of Technology, 1200 E. California Blvd, Pasadena, CA 91125, United States
AB: Isoprene is the single largest non-methane volatile organic carbon source to the atmosphere. Its flux from terrestrial ecosystems is sensitive to temperature, water, and light levels and thus its emissions may be significantly altered by climate change. The oxidation of isoprene, typically initiated by reaction with the hydroxyl radical, broadly influences atmospheric composition. Several recent studies suggesting that oxidation products of isoprene yield significant secondary organic aerosol have fueled renewed interest in its oxidation chemistry. We describe the development and testing of an explicit mechanism of the photooxidation of isoprene initiated by reaction with the hydroxyl radical. We evaluate our mechanism with observations obtained in the Caltech environmental chamber of the time dependent evolution of numerous volatile organic compounds with a novel CIMS technique. Many of these compounds have not previously been observed. Experiments include oxidation in atmospheres with both initially low and high NOx concentrations, providing a comprehensive test of the mechanism. Special emphasis is placed on unraveling the production and loss mechanisms of organic nitrates and acids. Finally, we test several hypotheses on the chemistry leading o aerosol formation.
DE: 0305 Aerosols and particles (0345, 4801, 4906)
DE: 0315 Biosphere/atmosphere interactions (0426, 1610)
DE: 0317 Chemical kinetic and photochemical properties
DE: 0365 Troposphere: composition and chemistry
SC: Atmospheric Sciences [A]
MN: 2007 Fall Meeting