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| Titel |
Source-receptor relationships between East Asian sulfur dioxide emissions and Northern Hemisphere sulfate concentrations |
| VerfasserIn |
J. Liu, D. L. Mauzerall, L. W. Horowitz |
| 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 ; 8, no. 14 ; Nr. 8, no. 14 (2008-07-15), S.3721-3733 |
| Datensatznummer |
250006280
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| Publikation (Nr.) |
 copernicus.org/acp-8-3721-2008.pdf |
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| Zusammenfassung |
| We analyze the effect of varying East Asian (EA) sulfur emissions on sulfate
concentrations in the Northern Hemisphere, using a global coupled
oxidant-aerosol model (MOZART-2). We conduct a base and five sensitivity
simulations, in which sulfur emissions from each continent are tagged, to
establish the source-receptor (S-R) relationship between EA sulfur emissions
and sulfate concentrations over source and downwind regions. We find that
from west to east across the North Pacific, EA sulfate contributes
approximately 80%–20% of sulfate at the surface, but at least 50%
at 500 hPa. Surface sulfate concentrations are dominated by local
anthropogenic sources. Of the sulfate produced from sources other than local
anthropogenic emissions (defined here as "background" sulfate), EA sources
account for approximately 30%–50% (over the Western US) and
10%–20% (over the Eastern US). The surface concentrations of sulfate
from EA sources over the Western US are highest in MAM (up to 0.15 μg/m3),
and lowest in DJF (less than 0.06 μg/m3). Reducing EA
SO2 emissions will significantly decrease the spatial extent of the EA
sulfate influence (represented by the areas where at least 0.1 μg m−3
of sulfate originates from EA) over the North Pacific
both at the surface and at 500 hPa in all seasons, but the extent of
influence is insensitive to emission increases, particularly in DJF and JJA.
We find that EA sulfate concentrations over most downwind regions respond
nearly linearly to changes in EA SO2 emissions, but sulfate
concentrations over the EA source region increase more slowly than SO2
emissions, particularly at the surface and in winter, due to limited
availability of oxidants (in particular of H2O2, which oxidizes
SO2 to sulfate in the aqueous phase). We find that similar estimates of
the S-R relationship for trans-Pacific transport of EA sulfate would be
obtained using either sensitivity (i.e., varying emissions from a region to
examine the effects on downwind concentrations) or tagging techniques. Our
findings suggest that future changes in EA sulfur emissions may cause little
change in the sulfate-induced health impact over downwind continents.
However, SO2 emission reductions may significantly reduce the sulfate
concentrations and the resulting negative radiative forcing over the North
Pacific and the United States, thus providing a warming tendency. |
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