 |
| Titel |
Atmospheric nitrogen oxides (NO and NO2) at Dome C, East Antarctica, during the OPALE campaign |
| VerfasserIn |
M. M. Frey, H. K. Roscoe, A. Kukui, J. Savarino, J. L. France, M. D. King, M. Legrand, S. Preunkert |
| Medientyp |
Artikel
|
| Sprache |
Englisch
|
| ISSN |
1680-7316
|
| Digitales Dokument |
URL |
| Erschienen |
In: Atmospheric Chemistry and Physics ; 15, no. 14 ; Nr. 15, no. 14 (2015-07-17), S.7859-7875 |
| Datensatznummer |
250119906
|
| Publikation (Nr.) |
 copernicus.org/acp-15-7859-2015.pdf |
|
|
|
|
|
| Zusammenfassung |
| Mixing ratios of the atmospheric nitrogen oxides NO and NO2 were measured
as part of the OPALE (Oxidant Production in Antarctic Lands & Export)
campaign at Dome C, East Antarctica (75.1° S, 123.3° E,
3233 m), during December 2011 to January 2012. Profiles of NOx
mixing ratios of the lower 100 m of the atmosphere confirm that, in
contrast to the South Pole, air chemistry at Dome C is strongly influenced by
large diurnal cycles in solar irradiance and a sudden collapse of the
atmospheric boundary layer in the early evening. Depth profiles of mixing
ratios in firn air suggest that the upper snowpack at Dome C holds
a significant reservoir of photolytically produced NO2 and is a sink of
gas-phase ozone (O3). First-time observations of bromine oxide (BrO) at Dome C show that
mixing ratios of BrO near the ground are low, certainly less than
5 pptv, with higher levels in the free troposphere. Assuming
steady state, observed mixing ratios of BrO and RO2 radicals are too low
to explain the large NO2 : NO ratios found in ambient air, possibly
indicating the existence of an unknown process contributing to the
atmospheric chemistry of reactive nitrogen above the Antarctic Plateau.
During 2011–2012, NOx mixing ratios and flux were larger than in
2009–2010, consistent with also larger surface O3 mixing ratios resulting
from increased net O3 production. Large NOx mixing ratios at Dome C
arise from a combination of continuous sunlight, shallow mixing height and
significant NOx emissions by surface snow (FNOx). During
23 December 2011–12 January 2012, median FNOx was twice that
during the same period in 2009–2010 due to significantly larger atmospheric
turbulence and a slightly stronger snowpack source. A tripling of
FNOx in December 2011 was largely due to changes in snowpack
source strength caused primarily by changes in NO3− concentrations in the
snow skin layer, and only to a secondary order by decrease of total column
O3 and associated increase in NO3− photolysis rates. A source of
uncertainty in model estimates of FNOx is the quantum yield of
NO3− photolysis in natural snow, which may change over time as the snow
ages. |
| |
|
| Teil von |
|
|
|
|
|
|
|
|