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JOURNAL OF GEOPHYSICAL RESEARCH, VOL. 105, NO. D9, PAGES 11,585–11,600, 2000

Impact of acetone on ozone production and OH in the upper troposphere at high NO_x

Ian Folkins

Atmospheric Science Program, Departments of Physics and Oceanography, Dalhousie University Halifax, Nova Scotia, Canada

Robert Chatfield

Earth Science Division, NASA Ames Research Center, Moffett Field, California

Abstract

The impact of acetone (or any HO_x source) on tropospheric photochemistry is largest in the high NO_x regime. The fractional increases in OH and ozone production associated with acetone increase rapidly with NO_x when NO_x mixing ratios become larger than 300 parts per trillion by volume (pptv). This occurs in part because the HO_x yield of acetone is larger at higher NO_x mixing ratios, going from about 1HO_x at NO_x∼10 pptv to 3HO_x at NO_x∼1000 pptv. We also investigate the effect of acetone on the partitioning of the NO_y family. Acetone increases the conversion of NO to NO₂, HNO₄, HNO₃, and peroxyacetylnitrate (PAN). Conversion of NO to PAN dominates at low NO_x, while conversion of NO to HNO₃ dominates at high NO_x. These NO decreases significantly diminish the increases in OH and ozone production one would otherwise anticipate from the increases in HO₂. In particular, acetone can be expected to reduce ozone production for NO_x<25 pptv. We also show that most of the changes in species concentrations arising from the introduction of a HO_x source can be accurately predicted using simple expressions derived from linear perturbation theory. © 2000 American Geophysical Union

Index Terms: 0322 Atmospheric Composition and Structure: Constituent sources and sinks; 0365 Atmospheric Composition and Structure: Troposphere--composition and chemistry; 0368 Atmospheric Composition and Structure: Troposphere--constituent transport and chemistry; 3210 Mathematical Geophysics: Modeling.

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Citation: Folkins, I., and R. Chatfield, Impact of acetone on ozone production and OH in the upper troposphere at high NOx, J. Geophys. Res., 105(D9), 11,585–11,600, 2000.

Copyright 2000 by the American Geophysical Union.