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| Titel |
A multi-resolution assessment of the Community Multiscale Air Quality (CMAQ) model v4.7 wet deposition estimates for 2002–2006 |
| VerfasserIn |
K. W. Appel, K. M. Foley, J. O. Bash, R. W. Pinder, R. L. Dennis, D. J. Allen, K. Pickering |
| 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 ; 4, no. 2 ; Nr. 4, no. 2 (2011-05-03), S.357-371 |
| Datensatznummer |
250001658
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| Publikation (Nr.) |
 copernicus.org/gmd-4-357-2011.pdf |
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| Zusammenfassung |
| This paper examines the operational performance of the Community Multiscale
Air Quality (CMAQ) model simulations for 2002–2006 using both 36-km and
12-km horizontal grid spacing, with a primary focus on the performance of
the CMAQ model in predicting wet deposition of sulfate (SO4=),
ammonium (NH4+) and nitrate (NO3−). Performance of the
wet deposition estimates from the model is determined by comparing CMAQ
predicted concentrations to concentrations measured by the National Acid
Deposition Program (NADP), specifically the National Trends Network (NTN).
For SO4= wet deposition, the CMAQ model estimates were generally
comparable between the 36-km and 12-km simulations for the eastern US,
with the 12-km simulation giving slightly higher estimates of SO4=
wet deposition than the 36-km simulation on average. The result is a
slightly larger normalized mean bias (NMB) for the 12-km simulation; however
both simulations had annual biases that were less than ±15 % for
each of the five years. The model estimated SO4= wet deposition
values improved when they were adjusted to account for biases in the model
estimated precipitation. The CMAQ model underestimates NH4+ wet
deposition over the eastern US, with a slightly larger underestimation in
the 36-km simulation. The largest underestimations occur in the winter and
spring periods, while the summer and fall have slightly smaller
underestimations of NH4+ wet deposition. The underestimation in
NH4+ wet deposition is likely due in part to the poor temporal and
spatial representation of ammonia (NH3) emissions, particularly those
emissions associated with fertilizer applications and NH3
bi-directional exchange. The model performance for estimates of
NO3− wet deposition are mixed throughout the year, with the model
largely underestimating NO3− wet deposition in the spring and
summer in the eastern US, while the model has a relatively small bias in
the fall and winter. Model estimates of NO3− wet deposition tend
to be slightly lower for the 36-km simulation as compared to the 12-km
simulation, particularly in the spring. The underestimation of
NO3− wet deposition in the spring and summer is due in part to a
lack of lightning generated NO emissions in the upper troposphere, which can
be a large source of NO in the spring and summer when lightning activity is
the high. CMAQ model simulations that include production of NO from
lightning show a significant improvement in the NO3− wet
deposition estimates in the eastern US in the summer. Overall, performance
for the 36-km and 12-km CMAQ model simulations is similar for the eastern
US, while for the western US the performance of the 36-km simulation is
generally not as good as either eastern US simulation, which is not entire
unexpected given the complex topography in the western US. |
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