Removals of stratospheric O3 by radicals - In situ measurements of OH, HO2, NO, NO2, ClO, and BrO

• Published in: Science (American Association for the Advancement of Science) Vol. 266; no. 5184; pp. 398 - 404
• Main Authors: Wennberg, P O, Cohen, R C, Stimpfle, R M, Koplow, J P, Anderson, J G, Salawitch, R J, Fahey, D W, Woodbridge, E L, Keim, E R, Gao, R S
• Format: Journal Article
• Language: English
• Published: 21-10-1994
• ISSN: 0036-8075

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 is demonstrated on the basis of simultaneous in situ measurements of the concentrations of OH, HO2, ClO, BrO, NO, and NO2. A single catalytic cycle, in which the rate-limiting step is the reaction of HO2 with ozone, accounted for nearly one-half of the total O3 removal in this region of the atmosphere. Halogen-radical chemistry was responsible for about one-third of the photochemical removal of O3; reactions involving BrO account for one-half of this loss. The measurements demonstrate quantitatively the coupling that exists between the radical families. It is also shown that in the air sampled, the rate of O3 removal was inversely correlated with total NO(x) loading. (AIAA)