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| Titel |
Observations of hydroxyl and peroxy radicals and the impact of BrO at Summit, Greenland in 2007 and 2008 |
| VerfasserIn |
J. Liao, L. G. Huey, D. J. Tanner, N. Brough, S. Brooks, J. E. Dibb, J. Stutz, J. L. Thomas, B. Lefer, C. Haman, K. Gorham |
| 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 ; 11, no. 16 ; Nr. 11, no. 16 (2011-08-23), S.8577-8591 |
| Datensatznummer |
250010022
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| Publikation (Nr.) |
 copernicus.org/acp-11-8577-2011.pdf |
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| Zusammenfassung |
| The Greenland Summit Halogen-HOx (GSHOX) Campaign was performed in
spring 2007 and summer 2008 to investigate the impact of halogens on
HOx (= OH + HO2) cycling above the Greenland Ice Sheet. Chemical
species including hydroxyl and peroxy radicals (OH and HO2 + RO2),
ozone (O3), nitrogen oxide (NO), nitric acid (HNO3), nitrous acid
(HONO), reactive gaseous mercury (RGM), and bromine oxide (BrO) were
measured during the campaign. The median midday values of HO2 + RO2
and OH concentrations observed by chemical ionization mass spectrometry
(CIMS) were 2.7 × 108 molec cm−3 and 3.0 × 106 molec cm−3 in spring 2007, and 4.2 × 108 molec cm−3
and 4.1 × 106 molec cm−3 in summer 2008. A basic
photochemical 0-D box model highly constrained by observations of H2O,
O3, CO, CH4, NO, and J values predicted HO2 + RO2 (R = 0.90, slope = 0.87 in 2007; R = 0.79, slope = 0.96 in 2008) reasonably well
and under predicted OH (R = 0.83, slope = 0.72 in 2007; R = 0.76,
slope = 0.54 in 2008). Constraining the model to HONO observations did not
significantly improve the ratio of OH to HO2 + RO2 and the
correlation between predictions and observations. Including bromine
chemistry in the model constrained by observations of BrO improved the
correlation between observed and predicted HO2 + RO2 and OH, and
brought the average hourly OH and HO2 + RO2 predictions closer to
the observations. These model comparisons confirmed our understanding of the
dominant HOx sources and sinks in this environment and indicated that
BrO impacted the OH levels at Summit. Although, significant discrepancies
between observed and predicted OH could not be explained by the measured
BrO. Finally, observations of enhanced RGM were found to be coincident with
under prediction of OH. |
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