HO2NO2 and HNO3 in the coastal Antarctic winter night: a "lab-in-the-field" experiment

Jones, A. E. and Brough, N. and Anderson, P. S. and Wolff, E. W. (2014) HO2NO2 and HNO3 in the coastal Antarctic winter night: a "lab-in-the-field" experiment. Atmospheric Chemistry and Physics, 14 (21). pp. 11843-11851. ISSN 1680-7316 eISSN 1680-7324 DOI 10.5194/acp-14-11843-2014

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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.

Item Type:	Article
Uncontrolled Keywords:	2014AREP; IA68;
Subjects:	01 - Climate Change and Earth-Ocean Atmosphere Systems
Divisions:	01 - Climate Change and Earth-Ocean Atmosphere Systems 07 - Gold Open Access
Journal or Publication Title:	Atmospheric Chemistry and Physics
Volume:	14
Page Range:	pp. 11843-11851
Identification Number:	10.5194/acp-14-11843-2014
Depositing User:	Sarah Humbert
Date Deposited:	06 Feb 2015 17:33
Last Modified:	16 Feb 2015 18:21
URI:	http://eprints.esc.cam.ac.uk/id/eprint/3238

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