 |
| Titel |
Seasonal observations of OH and HO2 in the remote tropical marine boundary layer |
| VerfasserIn |
S. Vaughan, T. Ingham, L. K. Whalley, D. Stone, M. J. Evans, K. A. Read, J. D. Lee, S. J. Moller, L. J. Carpenter, A. C. Lewis, Z. L. Fleming, D. E. Heard |
| Medientyp |
Artikel
|
| Sprache |
Englisch
|
| ISSN |
1680-7316
|
| Digitales Dokument |
URL |
| Erschienen |
In: Atmospheric Chemistry and Physics ; 12, no. 4 ; Nr. 12, no. 4 (2012-02-27), S.2149-2172 |
| Datensatznummer |
250010744
|
| Publikation (Nr.) |
 copernicus.org/acp-12-2149-2012.pdf |
|
|
|
|
|
| Zusammenfassung |
| Field measurements of the hydroxyl radical, OH, are crucial for our
understanding of tropospheric chemistry. However, observations of this key
atmospheric species in the tropical marine boundary layer, where the warm,
humid conditions and high solar irradiance lend themselves favourably to
production, are sparse. The Seasonal Oxidant Study at the Cape Verde
Atmospheric Observatory in 2009 allowed, for the first time, seasonal
measurements of both OH and HO2 in a clean (i.e. low NOx),
tropical marine environment. It was found that concentrations of OH and
HO2 were typically higher in the summer months (June, September), with
maximum daytime concentrations of ~9 × 106 and 4 × 108 molecule cm−3, respectively – almost double the values in
winter (late February, early March). HO2 was observed to persist at
~107 molecule cm−3 through the night, but there was no
strong evidence of nighttime OH, consistent with previous measurements at
the site in 2007. HO2 was shown to have excellent correlations
(R2 ~ 0.90) with both the photolysis rate of ozone, J(O1D),
and the primary production rate of OH, P(OH), from the reaction of O(1D)
with water vapour. The analogous relations of OH were not so strong
(R2 ~ 0.6), but the coefficients of the linear correlation with
J(O1D) in this study were close to those yielded from previous works in
this region, suggesting that the chemical regimes have similar impacts on
the concentration of OH. Analysis of the variance of OH and HO2 across
the Seasonal Oxidant Study suggested that ~70% of the total
variance could be explained by diurnal behaviour, with ~30% of the
total variance being due to changes in air mass. |
| |
|
| Teil von |
|
|
|
|
|
|
|
|