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| Titel |
Intercontinental transport of pollution and dust aerosols: implications for regional air quality |
| VerfasserIn |
Mian Chin, T. Diehl, P. Ginoux, W. Malm |
| 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 ; 7, no. 21 ; Nr. 7, no. 21 (2007-11-01), S.5501-5517 |
| Datensatznummer |
250005241
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| Publikation (Nr.) |
 copernicus.org/acp-7-5501-2007.pdf |
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| Zusammenfassung |
| We use the global model GOCART to examine the impact of pollution and dust
aerosols emitted from their major sources on surface fine particulate matter
concentrations at regional and hemispheric scales. Focusing on the North
America region in 2001, we use measurements from the IMPROVE network in the
United States to evaluate the model-simulated surface concentrations of the
"reconstructed fine mass" (RCFM) and its components of ammonium sulfate,
black carbon (BC), organic matter (OM), and fine mode dust. We then quantify
the RCFM budget in terms of the RCFM chemical composition, source type, and
region of origin to find that in the eastern U.S., ammonium sulfate is the
dominant RCFM component (~60%) whereas in the western U.S., dust
and OM are just as important as sulfate but have considerable seasonal
variations, especially in the NW. On an annual average, pollution aerosol
(defined as aerosols from fuel combustion for industrial and transportation
uses) from North America accounts for 65–70% of the surface RCFM in
the eastern U.S. and for a lower proportion of 30–40% in the western
U.S.; by contrast, pollution from outside of North America contributes to
just 2–6% (~0.2 μg m−3) of the total RCFM over the
U.S. In comparison, long-range transport of dust brings 3 to 4 times more
fine particles than the transport of pollution to the U.S. (0.5–0.8 μg m−3
on an annual average) with a maximum influence in spring and
over the NW. Of the major pollution regions, Europe has the largest
potential to affect the surface aerosol concentrations in other continents
due to its shorter distance from receptor continents and its larger fraction
of sulfate-producing precursor gas in the outflow. With the IPCC emission
scenario for the year 2000, we find that European emissions increase levels
of ammonium sulfate by 1–5 μg m−3 over the surface of northern
Africa and western Asia, and its contribution to eastern Asia (≥0.2 μg m−3) is twice as much as the Asian contribution to North
America. Asia and North America pollution emissions exert strong impacts on
their neighboring oceans, but their influences over other continents are
relatively small (≤10%) due to long traveling distances across the
oceans and efficient removal during transport. Among the major dust source
regions, Asia displays a significant influence over large areas in the
northern hemisphere except over the North Atlantic and the tropics, where
African dust dominates. We also notice that the African dust and European
pollution can travel eastward through a pathway spanning across Asia and
North Pacific to western North America; such a pathway is difficult to
detect because these aerosols usually merge and travel together with Asian
dust and pollution labeled as "Asian outflow". |
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