HR: 1340h
AN: A43C-0063    [Abstracts]
TI: Chemical processes in a smoke plume from a savanna fire
AU: * Trentmann, J
EM: jtrent@atmos.washington.edu
AF: Dept. of Atmospheric Sciences, University of Washington,Box 351640, Seattle, WA 98195 United States
AU: Yokelson, R J
EM: byok@selway.umt.edu
AF: Dept. of Chemistry, University of Missoula, Missoula, MT 59812 United States
AU: Hobbs, P V
EM: phobbs@atmos.washington.edu
AF: Dept. of Atmospheric Sciences, University of Washington,Box 351640, Seattle, WA 98195 United States
AU: Winterrath, T
EM: tanja.winterrath@dwd.de
AF: Max Planck Institute for Chemistry, Postfach 3060, Mainz, 55128 Germany
AU: Christian, T J
EM: ted.christian@umontana.edu
AF: Dept. of Chemistry, University of Missoula, Missoula, MT 59812 United States
AU: Andreae, M O
EM: andreae@mpch-mainz.mpg.de
AF: Max Planck Institute for Chemistry, Postfach 3060, Mainz, 55128 Germany
AU: Mason, S A
EM: sherri.mason@Fredonia.edu
AF: SUNY College at Fredonia, 220 Houghton Hall, Fredonia, NY 14063 United States
AB: Gaseous emissions from wildfires include a wide range of organic compounds, including oxygenated VOCs, and nitrogen oxides. Chemical processes in young plumes from fires significantly modify the initial emissions. Field measurements performed in the smoke plume from the Timbavati fire during SAFARI 2000 using the Airborne Fourier Transform Infrared Spectrometer (AFTIR) onboard the University of Washington's Convair-580 aircraft show significant increases in the enhancement ratios of ozone and acetic acid with respect to CO during the first hour following the emission into the atmosphere. Decreases in enhancement ratios have been measured for a number of hydrocarbons. Investigating the chemical reactions that lead to these fast changes helps to improve our present understanding of tropospheric photochemistry. Here, we present results from model simulations using a detailed photochemical box-dilution model constrained to the field observations. Using known photochemical processes, the model underestimates the observed production of ozone and acetic acid, even if radiative effects of the smoke aerosol and uncertainties in the emissions are taken into account. Introduction of a recently proposed heterogeneous reaction between NO$_2$ and methanol significantly improves the comparison for ozone. Several potential sources for acetic acid are discussed including production of acetate in the particulate phase and subsequent degassing. These investigations point to the importance of the interactions between the gas and aerosol phase for the photochemistry in young smoke plumes and potentially in other environments, and highlight the importance of further field and laboratory experiments.
DE: 0305 Aerosols and particles (0345, 4801)
DE: 0317 Chemical kinetic and photochemical properties
DE: 0322 Constituent sources and sinks
DE: 0365 Troposphere--composition and chemistry
SC: Atmospheric Sciences [A]
MN: 2004 AGU Fall Meeting