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Berhanu Tesfaye. (2013). An isotopic approach towards understanding nitrate formation pathways and revealing the photochemistry of nitrate in snow.
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Vicars, W., Savarino, J., Erbland, J., Preunkert, S., Jourdain, B., Frey, M., Gil Roca, J., and Legrand, M.: . (2013). Oxygen isotope dynamics of atmospheric nitrate over the Antarctic plateau: First combined measurements of ozone and nitrate 17O-excess (Δ17O), EGU General Assembly, Vienna, Austria
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Shaheen, R., Abauna-Quintero, M., Jackson, T., McCabe, A. M., Savarino, J., and Thiemens, H. M.:
. (2013). Delineating Understanding the effect of El-Nino Southern Oscillations on the oxidation history of sulfate aerosols, AGU, General Assembly, San Francisco.
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Preunkert, S., Kukui, A., Legrand, M., Frey, M., Bekki, S., Savarino, J., Ancellet, G., Thomas, J. L., Gil Roca, J., Kerbrat, M., Jourdain, B., Loisil, R., France, J., and King, M. D.:
. (2013). 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., EGU General Assembly, Vienna, Austria.
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Helmig, D., Mass, A., Hueber, J., Faïn, X., Dommergue, A., Barbero, A., and Savarino, J.:
. (2013). Snowpack Chemistry of Reactive Gases at Station Concordia, Antarctica, EGU General Assembly, Vienna, Austria.
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Gil Roca, J., Thomas, J. L., Bekki, S., Kukui, A., Ancellet, G., Preunkert, S., Legrand, M., Frey, M., Savarino, J., Jourdain, B., Kerbrat, M., France, J., King, M. D., and Toumi, R.: . (2013). Lagrangian modelling of OPALE dataset., EGU General Assembly, Vienna, Austria
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Frey, M., Brough, N., Kukui, A., Gil Roca, J., Savarino, J., and Preunkert, S.: . (2013). Summer emissions of nitrogen oxides from snow at Dome C (East Antarctica): a discussion of seasonal variability, EGU General Assembly, Vienna, Austria
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Legrand M, Preunkert S, Frey M, Bartels-Rausch Th, Kukui A, King M D, Savarino J, Kerbrat M, Jourdain B, . (2014). Large mixing ratios of atmospheric nitrous acid (HONO) at Concordia (East Antarctic Plateau) in summer: a strong source from surface snow?
. 1680-7316, 14(18), 9963–9976.
Abstract: During the austral summer 2011/2012 atmospheric nitrous acid (HONO) was investigated for the second
time at the Concordia site (75060 S, 123330 E), located on the East Antarctic Plateau, by deploying a long-path absorption photometer (LOPAP). Hourly mixing ratios of HONO measured in December 2011/January 2012 (35±5.0 pptv) were similar to those measured in December 2010/January
2011 (30.4±3.5 pptv). The large value of the HONO mixing ratio at the remote Concordia site suggests a local source of HONO in addition to weak production from oxidation of
NO by the OH radical. Laboratory experiments demonstrate that surface snow removed from Concordia can produce gasphase HONO at mixing ratios half that of the NOx mixing ratio produced in the same experiment at typical temperatures encountered at Concordia in summer. Using these lab data and the emission flux of NOx from snow estimated from the vertical gradient of atmospheric concentrations measured during the campaign, a mean diurnal HONO snow emission ranging between 0.5 and 0.8×109 molecules cm-2 s-1 is calculated. Model calculations indicate that, in addition to around 1.2 pptv of HONO produced by the NO oxidation, these HONO snow emissions can only explain 6.5 to 10.5 pptv of HONO in the atmosphere at Concordia. To explain the difference between observed and simulated HONO mixing ratios, tests were done both in the field and at lab to explore the possibility that the presence of HNO4 had biased the measurements of HONO.
Programme: 1011
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Shaheen R, Abaunza M M, Jackson T L, McCabe J, Savarino J, Thiemens M H, . (2014). Large sulfur-isotope anomaly in nonvolcanic sulfate aerosol and its implications for the Archean atmosphere
. 0027-8424, 111(33), 11979–11983.
Abstract: Sulfur-isotopic anomalies have been used to trace the evolution of oxygen in the Precambrian atmosphere and to document past volcanic eruptions. High-precision sulfur quadruple isotope measurements of sulfate aerosols extracted from a snow pit at the South Pole (1984-2001) showed the highest S-isotopic anomalies ({Delta}33S = +1.66{per thousand} and {Delta}36S = +2{per thousand}) in a nonvolcanic (1998-1999) period, similar in magnitude to Pinatubo and Agung, the largest volcanic eruptions of the 20th century. The highest isotopic anomaly may be produced from a combination of different stratospheric sources (sulfur dioxide and carbonyl sulfide) via SOx photochemistry, including photoexcitation and photodissociation. The source of anomaly is linked to super El Nino Southern Oscillation (ENSO) (1997-1998)-induced changes in troposphere-stratosphere chemistry and dynamics. The data possess recurring negative S-isotope anomalies ({Delta}36S = -0.6 {+/-} 0.2{per thousand}) in nonvolcanic and non-ENSO years, thus requiring a second source that may be tropospheric. The generation of nonvolcanic S-isotopic anomalies in an oxidizing atmosphere has implications for interpreting Archean sulfur deposits used to determine the redox state of the paleoatmosphere.
Programme: 1011
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Savarino, J., Berhanu, T. A., Meusinger, C., Johnson, M., Erbland, J., Jost, R., and Bhattacharya, S. K.:
. (2014). Nitrate photolysis of Antarctic snow: Isotopic effects and wavelength dependence, The 7th International Symposium on Isotopomers, Tokyo, Japan.
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