Stratospheric Bromine Chemistry
Contact: Nathaniel Livesey
Summary
Bromine chemistry is important in the catalytic destruction of stratospheric ozone, especially in the lower stratosphere (below about 20 km).
Model studies indicate that bromine catalytic cycles may account for as much as 60% of ozone loss for very cold Arctic winters. Bromine
monoxide (BrO), measured by EOS MLS, is the main daytime constituent of stratospheric inorganic bromine (Bry), making up about 50% of Bry. The other Bry constituents are Br, HOBr,
BrONO2, HBr, and BrCl. In contrast, for stratospheric inorganic chlorine (Cly), the reactive constituents (Cl and ClO) make up only a few percent of Cly.
To quantify the impact of inorganic bromine on stratospheric ozone loss, accurate measurements of its abundance are needed. However, because of their low abundances (several ppt),
relatively few measurements have been made of its constituents. Therefore Bry is typically estimated from
stratospheric measurements of BrO, combined with estimates of the other constituents from photochemical models.
One current problem in stratospheric bromine chemistry is that
estimates of Bry from measurements of stratospheric BrO obtained by various satellite and balloon-borne instruments show some disagreement. A second problem is that estimates of Bry from measurements of stratospheric BrO tend to exceed predictions of Bry based on measurements
of the organic source gases from which Bry is believed to be derived (CH3Br and halons). It is currently strongly suspected that there may be
additional sources of stratospheric inorganic bromine.
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Recent Results
Date: 31 October 2006
Total bromine in the stratosphere. Total stratospheric inorganic bromine (Bry) abundance estimates have been inferred from the combined analyses of EOS MLS BrO measurements and models. The 'best estimate' of total upper stratospheric bromine loading (based on JPL-2002 kinetics with the addition of a BrONO2 + O reaction) is 18.6 +/- 5.5 pptv for the period September 2004 to August 2005 and for latitudes from 55o S to 55o N. This implies a contribution of 3.0 +/- 5.5 pptv from sources other than long-lived CH3Br and halons. + Read more
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Relevant Pulbications
2007
- Kovalenko, L.J., N.J. Livesey, R.J. Salawitch, C. Camy-Peyret, M.P. Chipperfield, R.E. Cofield, M. Dorf, B.J. Drouin, L. Froidevaux, R.A. Fuller, F. Goutail, R.F. Jarnot, K. Jucks, B.W. Knosp, A. Lambert, I.A. MacKenzie, K. Pfeilsticker, J-P. Pommereau, W.G. Read, M.L. Santee, M.J. Schwartz, W.V. Snyder, R. Stachnik, P.C. Stek, P.A. Wagner, J.W. Waters, "Validation of the Aura Microwave Limb Sounder BrO observations in the stratosphere", vol 112, pgs. D24S41, 2007. Reprint
2006
- Livesey, N.J., L.J. Kovalenko, R.J. Salawitch, I.A. MacKenzie, M.P. Chipperfield, W.G. Read, R.F. Jarnot, J.W. Waters, "EOS Microwave Limb Sounder observations of upper stratospheric BrO: Implications for total bromine", vol 33, pgs. L20817, 2006. Reprint
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