Removal of stratospheric O{sub 3} by radicals: In situ measurements of OH, HO{sub 2}, NO, NO{sub 2}, ClO, and BrO
- Harvard Univ., Cambridge, MA (United States)
- National Oceanic and Atmospheric Administration Aeronomy Lab., Boulder, CO (United States); and others
Simultaneous in situ measurements of the concentrations of OH, HO{sub 2}, ClO, BrO, NO, and NO{sub 2} demonstrate the predominance of odd-hydrogen and halogen free-radical catalysis in determining the rate of removal of ozone in the lower stratosphere during May 1993. A single catalytic cycle, in which the rate-limiting step is the reaction of HO{sub 2} with ozone, accounted for nearly one-half of the total O{sub 3} removal in this region of the atmosphere. Halogen-radical chemistry was responsible for approximately one-third of the photochemical removal of O{sub 3}; reactions involving BrO account for one-half of this loss. Catalytic destruction by NO{sub 2}, which for two decades was considered to be the predominant loss process, accounted for less than 20 percent of the O{sub 3} removal. The measurements demonstrate quantitatively the coupling that exists between the radical families. The concentrations of HO{sub 2} and ClO are inversely correlated with those of NO and NO{sub 2}. The direct determination of the relative importance of the catalytic loss processes, combined with a demonstration of the reactions linking the hydrogen, halogen, and nitrogen radical concentrations, shows that in the air sampled the rate of O{sub 3} removal was inversely correlated with total NO{sub x} loading.
- Sponsoring Organization:
- USDOE
- OSTI ID:
- 86540
- Journal Information:
- Science, Journal Name: Science Journal Issue: 5184 Vol. 266; ISSN SCIEAS; ISSN 0036-8075
- Country of Publication:
- United States
- Language:
- English
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