Journal cover Journal topic
Atmospheric Chemistry and Physics An interactive open-access journal of the European Geosciences Union
Atmos. Chem. Phys., 14, 11843-11851, 2014
http://www.atmos-chem-phys.net/14/11843/2014/
doi:10.5194/acp-14-11843-2014
© Author(s) 2014. This work is distributed
under the Creative Commons Attribution 3.0 License.
Research article
12 Nov 2014
HO2NO2 and HNO3 in the coastal Antarctic winter night: a "lab-in-the-field" experiment
A. E. Jones1, N. Brough1, P. S. Anderson1,*, and E. W. Wolff1,** 1British Antarctic Survey, Natural Environment Research Council, Cambridge, UK
*now at: Scottish Association of Marine Science, Scottish Marine Institute, Oban, UK
**now at: Dept of Earth Sciences, University of Cambridge, Cambridge, UK
Abstract. Observations of peroxynitric acid (HO2NO2) and nitric acid (HNO3) were made during a 4 month period of Antarctic winter darkness at the coastal Antarctic research station, Halley. Mixing ratios of HNO3 ranged from instrumental detection limits to ~8 parts per trillion by volume (pptv), and of HO2NO2 from detection limits to ~5 pptv; the average ratio of HNO3 : HO2NO2 was 2.0(± 0.6) : 1, with HNO3 always present at greater mixing ratios than HO2NO2 during the winter darkness. An extremely strong association existed for the entire measurement period between mixing ratios of the respective trace gases and temperature: for HO2NO2, R2 = 0.72, and for HNO3, R2 = 0.70. We focus on three cases with considerable variation in temperature, where wind speeds were low and constant, such that, with the lack of photochemistry, changes in mixing ratio were likely to be driven by physical mechanisms alone. We derived enthalpies of adsorption (ΔHads) for these three cases. The average ΔHads for HNO3 was −42 ± 2 kJ mol−1 and for HO2NO2 was −56 ± 1 kJ mol−1; these values are extremely close to those derived in laboratory studies. This exercise demonstrates (i) that adsorption to/desorption from the snow pack should be taken into account when addressing budgets of boundary layer HO2NO2 and HNO3 at any snow-covered site, and (ii) that Antarctic winter can be used as a natural "laboratory in the field" for testing data on physical exchange mechanisms.

Citation: Jones, A. E., Brough, N., Anderson, P. S., and Wolff, E. W.: HO2NO2 and HNO3 in the coastal Antarctic winter night: a "lab-in-the-field" experiment, Atmos. Chem. Phys., 14, 11843-11851, doi:10.5194/acp-14-11843-2014, 2014.
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Short summary
We report observations of nitric acid and peroxynitric acid, in coastal Antarctica during winter. During winter, it is dark 24h per day, so there is no influence of sunlight on atmospheric composition. We show that observed variability in concentrations is highly correlated with changes in temperature. We derive enthalpies of adsorption and show they are consistent with those derived in laboratory studies. The Antarctic, during winter, is an ideal natural laboratory to study air-snow exchange.
We report observations of nitric acid and peroxynitric acid, in coastal Antarctica during...
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