HR: 10:50h
AN: A42B-02    [Abstracts]
TI: Evaluation of the Role of Acetone on HOx Chemistry in the Upper Troposphere
AU: * Xie, H
EM: hxie@rsmas.miami.edu
AF: Rosenstiel School of Marine and Atmospheric Science, University of Miami 4600 Rickenbacker Causeway, Miami, FL 33149 United States
AU: Rodriguez, J M
EM: jrodriguez@rsmas.miami.edu
AF: Rosenstiel School of Marine and Atmospheric Science, University of Miami 4600 Rickenbacker Causeway, Miami, FL 33149 United States
AU: Prather, M J
EM: mprather@uci.edu
AF: Department of Earth System Science, University of California, Irvine, Irvine, CA 92697 United States
AB: Several studies have indicated that photolysys of acetone atconcentrations of order hundreds of ppt could enhance total HOx (OH+HO2) production by up to 30 percent in the upper troposphere (UT). However, recent measurements of the acetone quantum yield at low temperatures (Blitz et al., Geophysical Research Letters, 31, L06111, doi:10.1029/2003GL018793, 2004) obtain significantly smaller values than previous temperature-independent measurements. In this work, we reevaluate the impact of acetone on HOx production in the UT. Calculations are performed with a photochemical box model constrained by aircraft measurements to estimate the sources of HOx for the Pacific Exploratory Mission-Tropics B (PEM-Tropics B). We carry out a total of ~1400 box model calculations, constrained by input from a merged file of aircraft measurements at a 1 minute resolution. Results show that the calculated contribution of acetone to HOx production is smaller with the new acetone quantum yield, as expected. The median percent contribution of acetone photolysis to HOx production is now more than a factor of 2 smaller than the contribution calculated with the old quantum yield. We present details of the role of acetone as a function of altitude and latitude, and extend our analysis to other aircraft campaigns, in order to assess our current understanding of upper tropospheric HOx chemistry in light of the recent kinetic data.
DE: 0317 Chemical kinetic and photochemical properties
DE: 0365 Troposphere--composition and chemistry
DE: 0368 Troposphere--constituent transport and chemistry
SC: Atmospheric Sciences [A]
MN: 2004 AGU Fall Meeting