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| Titel |
Atmospheric ammonia and particulate inorganic nitrogen over the United States |
| VerfasserIn |
C. L. Heald, J. L. Collett, T. Lee, K. B. Benedict, F. M. Schwandner, Y. Li, L. Clarisse, D. R. Hurtmans, M. Damme, C. Clerbaux, P.-F. Coheur, S. Philip, R. V. Martin, H. O. T. Pye |
| 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. 21 ; Nr. 12, no. 21 (2012-11-06), S.10295-10312 |
| Datensatznummer |
250011567
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| Publikation (Nr.) |
 copernicus.org/acp-12-10295-2012.pdf |
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| Zusammenfassung |
| We use in situ observations from the Interagency Monitoring of PROtected
Visual Environments (IMPROVE) network, the Midwest Ammonia Monitoring
Project, 11 surface site campaigns as well as Infrared Atmospheric Sounding
Interferometer (IASI) satellite measurements with the GEOS-Chem model to
investigate inorganic aerosol loading and atmospheric ammonia concentrations
over the United States. IASI observations suggest that current ammonia
emissions are underestimated in California and in the springtime in the
Midwest. In California this underestimate likely drives the underestimate in
nitrate formation in the GEOS-Chem model. However in the remaining
continental United States we find that the nitrate simulation is biased high
(normalized mean bias > = 1.0) year-round, except in Spring (due to the
underestimate in ammonia in this season). None of the uncertainties in
precursor emissions, the uptake efficiency of N2O5 on aerosols, OH
concentrations, the reaction rate for the formation of nitric acid, or the
dry deposition velocity of nitric acid are able to explain this bias. We find
that reducing nitric acid concentrations to 75% of their simulated values
corrects the bias in nitrate (as well as ammonium) in the US. However the
mechanism for this potential reduction is unclear and may be a combination of
errors in chemistry, deposition and sub-grid near-surface gradients. This
"updated" simulation reproduces PM and ammonia loading and captures the
strong seasonal and spatial gradients in gas-particle partitioning across the
United States. We estimate that nitrogen makes up 15−35% of inorganic fine
PM mass over the US, and that this fraction is likely to increase in the
coming decade, both with decreases in sulfur emissions and increases in
ammonia emissions. |
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