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Ozone Depletion Potential of CH3BrThe ozone depletion potential (ODP) of methyl bromide (CH3Br) can be determined by combining the model-calculated bromine efficiency factor (BEF) for CH3Br and its atmospheric lifetime. This paper examines how changes in several key kinetic data affect BEF. The key reactions highlighted in this study include the reaction of BrO + HO2, the absorption cross section of HOBr, the absorption cross section and the photolysis products of BrONO2, and the heterogeneous conversion of BrONO2 to HOBr and HNO3 on aerosol particles. By combining the calculated BEF with the latest estimate of 0.7 year for the atmospheric lifetime of CH3Br, the likely value of ODP for CH3Br is 0.39. The model-calculated concentration of HBr (approx. 0.3 pptv) in the lower stratosphere is substantially smaller than the reported measured value of about 1 pptv. Recent publications suggested models can reproduce the measured value if one assumes a yield for HBr from the reaction of BrO + OH or from the reaction of BrO + HO2. Although the evaluation concluded any substantial yield of HBr from BrO + HO2 is unlikely, for completeness, we calculate the effects of these assumed yields on BEF for CH3Br. Our calculations show that the effects are minimal: practically no impact for an assumed 1.3% yield of HBr from BrO + OH and 10% smaller for an assumed 0.6% yield from BrO + HO2.
Document ID
20000011654
Acquisition Source
Goddard Space Flight Center
Document Type
Reprint (Version printed in journal)
External Source(s)
Authors
Ko, Malcolm K. W.
(Atmospheric and Environmental Research, Inc. Cambridge, MA United States)
Sze, Nien Dak
(Atmospheric and Environmental Research, Inc. Cambridge, MA United States)
Scott, Courtney
(Atmospheric and Environmental Research, Inc. Cambridge, MA United States)
Rodriguez, Jose M.
(Atmospheric and Environmental Research, Inc. Cambridge, MA United States)
Weisenstein, Debra K.
(Atmospheric and Environmental Research, Inc. Cambridge, MA United States)
Sander, Stanley P.
(Jet Propulsion Lab., California Inst. of Tech. Pasadena, CA United States)
Date Acquired
August 19, 2013
Publication Date
November 20, 1998
Publication Information
Publication: Journal of Geophysical Research
Publisher: American Geophysical Union
Volume: 103
Issue: D21
ISSN: 0148-0227
Subject Category
Environment Pollution
Report/Patent Number
Paper-98JD02537
Funding Number(s)
CONTRACT_GRANT: NAS5-97039
Distribution Limits
Public
Copyright
Other

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