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| Titel |
The Oxidant Production over Antarctic Land and its Export (OPALE) project: An overview of data collected in summer 2010-2011 at Dumont d'Urville and 2011-2012 at Concordia. |
| VerfasserIn |
Susanne Preunkert, Alexandre Kukui, Michel Legrand, Markus Frey, Slimane Bekki, Joel Savarino, Gérard Ancellet, Jennie Thomas, Jaime Gil Roca, Bruno Jourdain, Michael Kerbrat, Rodrigue Loisil, James France, Martin King |
| Konferenz |
EGU General Assembly 2013
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 15 (2013) |
| Datensatznummer |
250079932
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| Zusammenfassung |
| The need to characterize the oxidative capacity of the atmosphere in the vast region of East
Antarctica motivated the OPALE initiative with investigations both at the top of the high
plateau (Concordia) and at the East coast (Dumont d’Urville). The top of the East Antarctic
plateau is a region where processes are suspected to differ from those already identified at the
South Pole, in particular the photo-denitrification of the surface snow. For instance,
in contrast to the South Pole experiencing 24-hour sunlight, the solar irradiance
at Concordia has a strong diurnal cycle. Concordia is also the inland site where
the longest sulfur derived aerosol record has been extracted from deep ice cores.
Regarding coastal site observations, it is suspected that the oxidative capacity of the
atmosphere is different in Eastern Antarctica due to the frequent occurrence of katabatic
flow. This has to be considered in studies dealing with year-round observations
carried out at coastal Antarctic regions where large oceanic DMS emissions take
place.
The first OPALE field campaign took place in January 2011 at the coastal site of Dumont
d’Urville. Measurements of OH, the sum of HO2+RO2, HONO, O3, H2O2, CH3OOH, and
HCHO, were done. Logistical problems, which followed a helicopter accident (occurred
28thOctober 2010), obliged us to cancel NOx measurement at the coast. The major finding of
this campaign is related to the observed high HOx levels. With 24 h means of 2 106 and 3 108
molecule cm-3 for OH and RO2, respectively, the OH and RO2 concentrations
observed at DDU are the highest ever seen at the Antarctic coast. The OH level
observed at DDU cannot be simply explained by the relatively high level of ozone
observed at this site in relation with an efficient transport of air masses coming from
inland Antarctica. The steady state calculations suggest a RO2 to OH conversion
mechanism equivalent to 30 pptv of NO to explain observed HOx concentrations. Such
rather high NO levels were confirmed by NO2 measurements made in January
2012.
During the second campaign carried out at Concordia in December 2011-January 2012,
investigations included OH and HO2+RO2 together with species relevant to discuss their
sources and sinks (NO, NO2, HONO, O3, H2O2, HCHO), surface meteorological parameters
and physic of the boundary layer, and photolysis rates. It has to be noted that HONO
was measured for the first time in Antarctica by using the long path absorption
photometer (LOPAP) technique. A few balloon experiments documented ozone and NOx
changes with height. These data for which a well-marked diurnal cycle was often
observed will allow a better understanding of the role of snow-pack emissions on
the oxidative properties of the atmosphere overlying the East Antarctic plateau. |
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