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| Titel |
Interactions of bromine, chlorine, and iodine photochemistry during ozone depletions in Barrow, Alaska |
| VerfasserIn |
C. R. Thompson, P. B. Shepson, J. Liao, L. G. Huey, E. C. Apel, C. A. Cantrell, F. Flocke, J. Orlando, A. Fried, S. R. Hall, R. S. Hornbrook, D. J. Knapp, R. L. Mauldin III, D. D. Montzka, B. C. Sive, K. Ullmann, P. Weibring, A. Weinheimer |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1680-7316
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| Digitales Dokument |
URL |
| Erschienen |
In: Atmospheric Chemistry and Physics ; 15, no. 16 ; Nr. 15, no. 16 (2015-08-28), S.9651-9679 |
| Datensatznummer |
250120000
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| Publikation (Nr.) |
 copernicus.org/acp-15-9651-2015.pdf |
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| Zusammenfassung |
| The springtime depletion of tropospheric ozone in the Arctic is known to be
caused by active halogen photochemistry resulting from halogen atom
precursors emitted from snow, ice, or aerosol surfaces. The role of bromine
in driving ozone depletion events (ODEs) has been generally accepted, but
much less is known about the role of chlorine radicals in ozone depletion
chemistry. While the potential impact of iodine in the High Arctic is more
uncertain, there have been indications of active iodine chemistry through
observed enhancements in filterable iodide, probable detection of
tropospheric IO, and recently, observation of snowpack photochemical
production of I2. Despite decades of research, significant uncertainty
remains regarding the chemical mechanisms associated with the
bromine-catalyzed depletion of ozone, as well as the complex interactions
that occur in the polar boundary layer due to halogen chemistry. To
investigate this, we developed a zero-dimensional photochemical model,
constrained with measurements from the 2009 OASIS field campaign in Barrow,
Alaska. We simulated a 7-day period during late March that included a full
ozone depletion event lasting 3 days and subsequent ozone recovery to study
the interactions of halogen radicals under these different conditions. In
addition, the effects of iodine added to our Base Model were investigated.
While bromine atoms were primarily responsible for ODEs, chlorine and iodine
were found to enhance the depletion rates and iodine was found to be more
efficient per atom at depleting ozone than Br. The interaction between
chlorine and bromine is complex, as the presence of chlorine can increase the
recycling and production of Br atoms, while also increasing reactive bromine
sinks under certain conditions. Chlorine chemistry was also found to have
significant impacts on both HO2 and RO2, with organic compounds
serving as the primary reaction partner for Cl atoms. The results of this
work highlight the need for future studies on the production mechanisms of
Br2 and Cl2, as well as on the potential impact of iodine in the
High Arctic. |
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