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Savarino, J., J. Erbland and B. Alexander. (2012). Changes in the oxidation capacity of the atmosphere revealed by stable isotopes in nitrate trapped in the Vostok ice core, paper presented at 5th International Symposium on Isotopomers.
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Vicars, W., S. K. Bhattacharya, J. Erbland and J. Savarino . (2012). Spatial and temporal variability in the 17O-excess (!17O) of surface ozone: Ambient measurements using the nitrite-coated filter method, paper presented at 5th International Symposium on Isotopomers, Washington, DC..
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Erbland, J., W. Vicars, J. Savarino, S. Morin, M. M. Frey, D. Frosini, E. Vince, and J. Martins . (2012). Air-snow transfer of nitrate on the East Antarctic Plateau – Part 1: Isotopic evidence for a photolytically driven dynamic equilibrium. 1680-7316, 12, 28559–28564.
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Savarino, J., J. Erbland, B. Alexander, L. Mickley, and L. Murray. (2012). Changes in the oxidation capacity of the atmosphere revealed by stable isotopes in nitrate trapped in the Vostok ice core, paper presented at 1st Open Science Conference International Partnership in Ice core Sciences, Giens, France..
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Vicars, W., S. K. Bhattacharya, J. Erbland, and J. Savarino. (2012). Spatial and temporal variability in the 17O-excess (Δ17O) of surface ozone: Ambient measurements using the nitrite-coated filter method, paper presented at 6th International Symposium on Isotopomers, Washington, DC.
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Meusinger, C., T. A. Berhanu, J. Erbland, F. Dominé, J. Savarino, and M. Johnson. (2012). Spatial and temporal variability in the 17O-excess (Δ17O) of surface ozone: Ambient measurements using the nitrite-coated filter method, paper presented at 6th International Symposium on Isotopomers, Washington, DC.
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Meusinger, C., T. A. Berhanu, J. Erbland, F. Dominé, J. Savarino, and M. Johnson. (2012). Photochemical Isotope Effects in Snowpack Nitrate, in EGU General Assembly, edited by EGU, pp. Abstract EGU2012-9821, poster, Vienna, Austria.
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Kaiser, J., A. Angert, B. A. Bergquist, W. Brand, S. Ono, T. Röckmann, and J. Savarino. (2012). IUPAC Project: Terminology and definition of quantities related to the isotope distribution in elements with more than two stable isotopes, in EGU General Assembly, edited by EGU, pp. Abstract EGU2012-14162-14162, poster, Vienna, Austria.
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Frey M M, Brough N, France J L, Anderson P S, Traulle O, King M D, Jones A E, Wolff E W, Savarino J, . (2013). The diurnal variability of atmospheric nitrogen oxides (NO and NO2) above the Antarctic Plateau driven by atmospheric stability and snow emissions
. ATMOSPHERIC CHEMISTRY AND PHYSICS, 13(6), 3045–3062.
Abstract: Atmospheric nitrogen oxides (NO and NO2) were observed at Dome C, East Antarctica (75.1° S, 123.3° E, 3233 m), for a total of 50 days, from 10 December 2009 to 28 January 2010. Average (±1σ) mixing ratios at 1.0 m of NO and NO2, the latter measured for the first time on the East Antarctic Plateau, were 111 (±89) and 98 (±89) pptv, respectively. Atmospheric mixing ratios are on average comparable to those observed previously at South Pole, but in contrast show strong diurnal variability: a minimum around local noon and a maximum in the early evening coincide with the development and collapse of a convective boundary layer. The asymmetric diurnal cycle of NOx concentrations and likely any other chemical tracer with a photolytic surface source is driven by the turbulent diffusivity and height of the atmospheric boundary layer, with the former controlling the magnitude of the vertical flux and the latter the size of the volume into which snow emissions are transported. In particular, the average (±1σ) NOx emission flux from 22 December 2009 to 28 January 2010, estimated from atmospheric concentration gradients, was 8.2 (±7.4) × 1012 molecule m-2 s-1 belongs to the largest values measured so far in the polar regions and explains the 3-fold increase in mixing ratios in the early evening when the boundary layer becomes very shallow. Dome C is likely not representative for the entire East Antarctic Plateau but illustrates the need of an accurate description of the boundary layer above snow in atmospheric chemistry models. A simple nitrate photolysis model matches the observed median diurnal NOx flux during the day but has significant low bias during the night. The difference is significant taking into account the total random error in flux observations and model uncertainties due to the variability of NO3- concentrations in snow and potential contributions from NO2- photolysis. This highlights uncertainties in the parameterization of the photolytic NOx source in natural snowpacks, such as the poorly constrained quantum yield of nitrate photolysis. A steady-state analysis of the NO2 : NO ratios indicates that peroxy (HO2 + RO2) or other radical concentrations in the boundary layer of Dome C are either higher than measured elsewhere in the polar regions or other processes leading to enhanced NO2 have to be invoked. These results confirm the existence of a strongly oxidising canopy enveloping the East Antarctic Plateau in summer.
Programme: 1011
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Hill-Falkenthal, J., A. Priyadarshi, J. Savarino, and M. H. Thiemens. (2013). Seasonal variations in 35S and Δ17O of sulfate aerosols on the Antarctic plateau. J. Geophys. Res. Atmos., .
Keywords: The first reported seasonal Δ17O anomaly in sulfate aerosols and measurements of radioactive 35SO42− activities collected from Dome C, Antarctica, are reported. Δ17O values exhibit minima during summer (as low as 0.91‰) when tropospheric oxidation patterns are dominated by OH/H2O2 mechanisms. Significant enrichment during autumn and spring is observed (up to 2.40‰) as ozone oxidation increases in the troposphere relative to summer and both stratospheric sources and long-range transport become more significant to the total sulfate budget. An unexpected decrease in Δ17O is seen as winter progresses. This decline is concluded to potentially arise due to a reduction in vertical mixing in the troposphere or linked to variations in the long-range transport of sulfur species to Antarctica. 35SO42− activities exhibit maxima during summer (up to 1219 atoms 35S/m3) that correlate with the peak in stratospheric flux and minima during winter (as low as 146 atoms 35S/m3) when the lack of solar radiation substantially reduces photochemical activity. It is shown that 35S offers the potential to be used as an additional tracer to study stratospheric and tropospheric interactions and is used to estimate stratospheric input of sulfur (combination of SO2 and SO42−). Stratospheric sulfur input produces maxima during summer/autumn with an upper limit of 5.5 ng/m3 and minima during winter/spring with an upper limit of 1.1 ng/m3. From these results, it is concluded that the variation in Δ17O is more reliant upon shifts in tropospheric oxidation mechanisms and long-range transport than on changes in the stratospheric flux.
Programme: 1011
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