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Impact of acetone on ozone production and OH in the upper troposphere at high NO x

2000; American Geophysical Union; Volume: 105; Issue: D9 Linguagem: Inglês

10.1029/2000jd900067

2156-2202

Ian Folkins, R. B. Chatfield,

Atmospheric and Environmental Gas Dynamics

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 1 HO x at NO x ∼ 10 pptv to 3 HO 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 NO 2 , HNO 4 , HNO 3 , and peroxyacetylnitrate (PAN). Conversion of NO to PAN dominates at low NO x , while conversion of NO to HNO 3 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 HO 2 . 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.