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| Titel |
Boundary layer new particle formation over East Antarctic sea ice – possible Hg-driven nucleation? |
| VerfasserIn |
R. S. Humphries, R. Schofield, M. D. Keywood, J. Ward, J. R. Pierce, C. M. Gionfriddo, M. T. Tate, D. P. Krabbenhoft, I. E. Galbally, S. B. Molloy, A. R. Klekociuk, P. V. Johnston, K. Kreher, A. J. Thomas, A. D. Robinson, N. R. P. Harris, R. Johnson, S. R. Wilson |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1680-7316
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| Digitales Dokument |
URL |
| Erschienen |
In: Atmospheric Chemistry and Physics ; 15, no. 23 ; Nr. 15, no. 23 (2015-12-02), S.13339-13364 |
| Datensatznummer |
250120199
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| Publikation (Nr.) |
 copernicus.org/acp-15-13339-2015.pdf |
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| Zusammenfassung |
| Aerosol observations above the Southern Ocean and Antarctic sea ice
are scarce. Measurements of aerosols and atmospheric composition
were made in East Antarctic pack ice on board the Australian
icebreaker Aurora Australis during the spring of 2012. One
particle formation event was observed during the 32 days of
observations. This event occurred on the only day to exhibit
extended periods of global irradiance in excess of
600 W m−2. Within the single air mass influencing the
measurements, number concentrations of particles larger than
3 nm (CN3) reached almost 7700 cm−3
within a few hours of clouds clearing, and grew at rates of
5.6 nm h−1. Formation rates of 3 nm particles
were in the range of those measured at other Antarctic locations at
0.2–1.1 ± 0.1 cm−3 s−1. Our investigations into
the nucleation chemistry found that there were insufficient
precursor concentrations for known halogen or organic chemistry to
explain the nucleation event. Modelling studies utilising known
sulfuric acid nucleation schemes could not simultaneously reproduce
both particle formation or growth rates. Surprising correlations
with total gaseous mercury (TGM) were found that, together with
other data, suggest a mercury-driven photochemical nucleation
mechanism may be responsible for aerosol nucleation. Given the very
low vapour pressures of the mercury species involved, this
nucleation chemistry is likely only possible where pre-existing
aerosol concentrations are low and both TGM concentrations and solar
radiation levels are relatively high (∼ 1.5 ng m−3
and ≥ 600 W m−2, respectively), such as those
observed in the Antarctic sea ice boundary layer in this study or in
the global free troposphere, particularly in the Northern
Hemisphere. |
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