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| Titel |
1D Chemical Modeling of coupled snow-atmosphere chemistry at Dome C Antarctica |
| VerfasserIn |
Jaime E. Gil, Jennie Thomas, Roland von Glasgow, Slimane Bekki, Alexandre Kukui, Markus Frey, Bruno Jourdain, Michel Kerbrat, Christophe Genthon, Susanne Preuknert, Michel Legrand |
| 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 |
250080671
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| Zusammenfassung |
| High levels of nitrogen oxides NOx (NOx=NO+NO2) generated by the photolysis of nitrate
present in surface snow profoundly impact atmospheric composition and oxidizing capacity
in the Antarctic boundary layer. In particular, NOx emissions from sunlit snow increase OH
values by effectively recycling HO2 to OH. In order to better characterize this chemistry the
OPALE campaign was conducted in December 2011/January 2012 at Dome C, Antarctica
(altitude of 3,233 meters, 75 Ë S, 123 Ë E). The campaign included boundary layer profiling,
measurements of the physical properties of snow, as well as a comprehensive suite of
atmospheric chemistry measurements (including NOx, HONO, OH and RO2, H2O2, CH2O,
O3).
We present results using the 1-D coupled snow-boundary layer model MISTRA-SNOW
in combination with observations made during the measurement campaign to understand
this chemistry. The model includes both chemistry at the surface of snow grains
(aqueous chemistry), in firn air (gas phase chemistry), and gas/aerosol chemistry in the
boundary layer. Model predictions of NOx mixing ratios using a model sensitivity
analysis approach are presented. The model was initialized using measured snow
properties, including temperature, density, and snow grain size. In addition, the
model dynamics are driven using the measured surface temperature at Dome C.
To calculate the rate of snowpack ventilation, measured wind speeds during the
campaign were used. The model was run varying the amount of nitrate and bromide
available for reaction at the surface of snow grains and results are compared to
measurements made in the atmospheric boundary from 2-4 January 2012. We test the
hypothesis that very low concentrations of bromine may alter the ratio of NO/NO2.
We also investigate the influence of NOx emissions from snow, and bromine (if
present), on OH concentrations in the boundary layer on the Antarctic plateau. |
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