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| Titel |
Evidence for Asian dust effects from aerosol plume measurements during INTEX-B 2006 near Whistler, BC |
| VerfasserIn |
W. R. Leaitch, A. M. Macdonald, K. G. Anlauf, P. S. K. Liu, D. Toom-Sauntry, S.-M. Li, J. Liggio, K. Hayden, M. A. Wasey, L. M. Russell, S. Takahama, S. Liu, A. Donkelaar, T. Duck, R. V. Martin, Q. Zhang, Y. Sun, I. McKendry, N. C. Shantz, M. Cubison |
| 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 ; 9, no. 11 ; Nr. 9, no. 11 (2009-06-03), S.3523-3546 |
| Datensatznummer |
250007350
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| Publikation (Nr.) |
 copernicus.org/acp-9-3523-2009.pdf |
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| Zusammenfassung |
| Several cases of aerosol plumes resulting from
trans-Pacific transport were observed between 2 km and 5.3 km at Whistler,
BC from 22 April 2006 to 15 May 2006. The fine particle (<1 μm)
chemical composition of most of the plumes was dominated by sulphate that
ranged from 1–5 μg m−3 as measured with a Quadrapole Aerosol Mass
Spectrometer (Q-AMS). Coarse particles (>1 μm) were enhanced in all
sulphate plumes. Fine particle organic mass concentrations were relatively
low in most plumes and were nominally anti-correlated with the increases in
the number concentrations of coarse particles. The ion chemistry of coarse
particles sampled at Whistler Peak was dominated by calcium, sodium,
nitrate, sulphate and formate. Scanning transmission X-ray microscopy of
coarse particles sampled from the NCAR C-130 aircraft relatively close to
Whistler indicated carbonate, potassium and organic functional groups, in
particular the carboxyl group. Asian plumes reaching Whistler, BC during the
INTEX-B study were not only significantly reduced of fine particle organic
material, but organic compounds were attached to coarse particles in
significant quantities. Suspension of dust with deposited organic material
and scavenging of organic materials by dust near anthropogenic sources are
suggested, and if any secondary organic aerosol (SOA) was formed during
transport from Asian source regions across the Pacific it was principally
associated with the coarse particles. An average of profiles indicates that
trans-Pacific transport between 2 and 5 km during this period increased
ozone by about 10 ppbv and fine particle sulphate by 0.2–0.5 μg m−3.
The mean sizes of the fine particles in the sulphate plumes were
larger when dust particles were present and smaller when the fine particle
organic mass concentration was larger and dust was absent. The coarse
particles of dust act to accumulate sulphate, nitrate and organic material
in larger particles, diminishing the role of these compounds in indirect
radiative forcing, but potentially enhancing their roles in direct radiative
forcing. |
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