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Titel |
HO2NO2 and HNO3 in the coastal Antarctic winter night: A “lab-in-the-field” experiment |
VerfasserIn |
Anna Jones, Neil Brough, Philip Anderson, Eric Wolff |
Konferenz |
EGU General Assembly 2015
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Medientyp |
Artikel
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Sprache |
Englisch
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Digitales Dokument |
PDF |
Erschienen |
In: GRA - Volume 17 (2015) |
Datensatznummer |
250102244
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Publikation (Nr.) |
EGU/EGU2015-1551.pdf |
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Zusammenfassung |
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 Â8 parts per trillion by
volume (pptv), and of HO2NO2 from detection limits to Â5 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±1kJ.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. |
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