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| Titel |
An MCM modeling study of nitryl chloride (ClNO2) impacts on oxidation, ozone production and nitrogen oxide partitioning in polluted continental outflow |
| VerfasserIn |
T. P. Riedel, G. M. Wolfe, K. T. Danas, J. B. Gilman, W. C. Kuster, D. M. Bon, A. Vlasenko, S.-M. Li, E. J. Williams, B. M. Lerner, P. R. Veres, J. M. Roberts, J. S. Holloway, B. Lefer, S. S. Brown, J. A. Thornton |
| 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 ; 14, no. 8 ; Nr. 14, no. 8 (2014-04-16), S.3789-3800 |
| Datensatznummer |
250118616
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| Publikation (Nr.) |
 copernicus.org/acp-14-3789-2014.pdf |
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| Zusammenfassung |
| Nitryl chloride (ClNO2) is produced at night by reactions of dinitrogen
pentoxide (N2O5) on chloride containing surfaces. ClNO2 is
photolyzed during the morning hours after sunrise to liberate highly
reactive chlorine atoms (Cl·). This chemistry takes place
primarily in polluted environments where the concentrations of
N2O5 precursors (nitrogen oxide radicals and ozone) are high,
though it likely occurs in remote regions at lower intensities. Recent field
measurements have illustrated the potential importance of ClNO2 as a
daytime Cl· source and a nighttime NOx reservoir. However,
the fate of the Cl· and the overall impact of ClNO2 on
regional photochemistry remain poorly constrained by measurements and
models. To this end, we have incorporated ClNO2 production, photolysis,
and subsequent Cl· reactions into an existing master chemical
mechanism (MCM version 3.2) box model framework using observational
constraints from the CalNex 2010 field study. Cl· reactions with a
set of alkenes and alcohols, and the simplified multiphase chemistry of
N2O5, ClNO2, HOCl, ClONO2, and Cl2, none of which
are currently part of the MCM, have been added to the mechanism. The
presence of ClNO2 produces significant changes to oxidants, ozone, and
nitrogen oxide partitioning, relative to model runs excluding ClNO2
formation. From a nighttime maximum of 1.5 ppbv ClNO2, the daytime
maximum Cl· concentration reaches 1 × 105 atoms cm−3 at
07:00 model time, reacting mostly with a large suite of volatile organic compounds (VOC)
to produce 2.2 times more organic peroxy radicals in the morning than in the
absence of ClNO2. In the presence of several ppbv of nitrogen oxide
radicals (NOx = NO + NO2), these perturbations lead to similar
enhancements in hydrogen oxide radicals (HOx = OH + HO2).
Neglecting contributions from HONO, the total integrated daytime radical
source is 17% larger when including ClNO2, which leads to a similar
enhancement in integrated ozone production of 15%. Detectable levels
(tens of pptv) of chlorine containing organic compounds are predicted to
form as a result of Cl· addition to alkenes, which may be useful
in identifying times of active Cl· chemistry. |
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