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Titel |
An evaluation of ambient ammonia concentrations over southern Ontario simulated with different dry deposition schemes within STILT-Chem v0.8 |
VerfasserIn |
D. Wen, L. Zhang, J. C. Lin, R. Vet, M. D. Moran |
Medientyp |
Artikel
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Sprache |
Englisch
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ISSN |
1991-959X
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Digitales Dokument |
URL |
Erschienen |
In: Geoscientific Model Development ; 7, no. 3 ; Nr. 7, no. 3 (2014-05-28), S.1037-1050 |
Datensatznummer |
250115628
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Publikation (Nr.) |
copernicus.org/gmd-7-1037-2014.pdf |
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Zusammenfassung |
A bidirectional air–surface exchange scheme for atmospheric ammonia
was incorporated into the Stochastic Time-Inverted Lagrangian
Transport air quality model (STILT-Chem v0.8). STILT-Chem v0.8 was
then applied to simulate atmospheric ammonia concentrations at 53
measurement sites in the province of Ontario, Canada for a six-month
period from 1 June to 30 November 2006. In addition to the
bidirectional scheme, two unidirectional dry deposition schemes
were tested. Comparisons of modeled ammonia concentrations against
observations show that all three schemes can reasonably predict
observations. For sites with low observed ammonia concentrations,
the bidirectional scheme clearly overestimated ammonia
concentrations during crop-growing season. Although all three schemes tended to underestimate
ammonia concentrations after mid-October and for sites with elevated observed
concentrations, mainly due to underestimated NH3 emission inventory after
mid-October and/or underestimated emission potentials for those sites, the
bidirectional scheme performed better because of its introduction of
compensation points into the flux
calculation parameterization. In addition to uncertainties in the emission inventory, the results of additional sensitivity
tests suggest that uncertainties in the input values of emission
potentials in the bidirectional scheme greatly affect the accuracy
of modeled ammonia concentrations. The use of much larger emission
potentials in the bidirectional scheme and larger anthropogenic NH3
emission after mid-October than provided in the model emissions files is needed for accurate
prediction of elevated ammonia concentrations at intensive
agricultural locations. |
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