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| Titel |
Multiphase modeling of nitrate photochemistry in the quasi-liquid layer (QLL): implications for NOx release from the Arctic and coastal Antarctic snowpack |
| VerfasserIn |
C. S. Boxe, A. Saiz-Lopez |
| 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 ; 8, no. 16 ; Nr. 8, no. 16 (2008-08-21), S.4855-4864 |
| Datensatznummer |
250006337
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| Publikation (Nr.) |
 copernicus.org/acp-8-4855-2008.pdf |
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| Zusammenfassung |
| We utilize a multiphase model, CON-AIR (Condensed Phase to
Air Transfer Model), to show that the photochemistry of nitrate
(NO3−) in and on ice and snow surfaces, specifically the
quasi-liquid layer (QLL), can account for NOx volume fluxes,
concentrations, and [NO]/[NO2] (γ=[NO]/[NO2]) measured just above the Arctic and coastal
Antarctic snowpack. Maximum gas phase NOx volume fluxes, concentrations
and γ simulated for spring and summer range from 5.0×104 to
6.4×105 molecules cm−3 s−1, 5.7×108 to 4.8×109 molecules cm−3,
and ~0.8 to 2.2, respectively, which are comparable to gas phase NOx
volume fluxes, concentrations and γ measured in the field. The model
incorporates the appropriate actinic solar spectrum, thereby properly
weighting the different rates of photolysis of NO3−
and NO2−. This is important since the immediate precursor
for NO, for example, NO2−, absorbs at wavelengths longer
than nitrate itself. Finally, one-dimensional model simulations indicate
that both gas phase boundary layer NO and NO2 exhibit a
negative concentration gradient as a function of height although
[NO]/[NO2] are approximately constant. This gradient is primarily
attributed to gas phase reactions of NOx with halogens oxides (i.e. as BrO
and IO), HOx, and hydrocarbons, such as CH3O2. |
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