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| Titel |
Nested-grid simulation of mercury over North America |
| VerfasserIn |
Y. Zhang, L. Jaeglé, A. Donkelaar, R. V. Martin, C. D. Holmes, H. M. Amos, Q. Wang, R. Talbot, R. Artz, S. Brooks, W. Luke, T. M. Holsen, D. Felton, E. K. Miller, K. D. Perry, D. Schmeltz, A. Steffen, R. Tordon, P. Weiss-Penzias, R. Zsolway |
| 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 ; 12, no. 14 ; Nr. 12, no. 14 (2012-07-16), S.6095-6111 |
| Datensatznummer |
250011315
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| Publikation (Nr.) |
 copernicus.org/acp-12-6095-2012.pdf |
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| Zusammenfassung |
| We have developed a new nested-grid mercury (Hg) simulation over North
America with a 1/2° latitude by 2/3° longitude
horizontal resolution employing the GEOS-Chem global chemical transport
model. Emissions, chemistry, deposition, and meteorology are self-consistent
between the global and nested domains. Compared to the global model
(4° latitude by 5° longitude), the nested model shows
improved skill at capturing the high spatial and temporal variability of Hg
wet deposition over North America observed by the Mercury Deposition Network
(MDN) in 2008–2009. The nested simulation resolves features such as
higher deposition due to orographic precipitation, land/ocean contrast and
and predicts more efficient convective rain scavenging of Hg over the
southeast United States. However, the nested model overestimates Hg wet
deposition over the Ohio River Valley region (ORV) by 27%. We modify
anthropogenic emission speciation profiles in the US EPA National Emission
Inventory (NEI) to account for the rapid in-plume reduction of reactive to
elemental Hg (IPR simulation). This leads to a decrease in the model bias to
−2.3% over the ORV region. Over the contiguous US, the correlation
coefficient (r) between MDN observations and our IPR simulation increases
from 0.60 to 0.78. The IPR nested simulation generally reproduces the
seasonal cycle in surface concentrations of speciated Hg from the
Atmospheric Mercury Network (AMNet) and Canadian Atmospheric Mercury Network
(CAMNet). In the IPR simulation, annual mean gaseous and particulate-bound
Hg(II) are within 140% and 11% of observations, respectively. In
contrast, the simulation with unmodified anthropogenic Hg speciation
profiles overestimates these observations by factors of 4 and 2 for gaseous
and particulate-bound Hg(II), respectively. The nested model shows improved
skill at capturing the horizontal variability of Hg observed over California
during the ARCTAS aircraft campaign. The nested model suggests that North
American anthropogenic emissions account for 10–22% of Hg wet deposition
flux over the US, depending on the anthropogenic emissions speciation
profile assumed. The modeled percent contribution can be as high as 60%
near large point sources in ORV. Our results indicate that the North
American anthropogenic contribution to dry deposition is 13–20%. |
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