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| Titel |
Evaluation of the Community Multiscale Air Quality (CMAQ) model v5.0 against size-resolved measurements of inorganic particle composition across sites in North America |
| VerfasserIn |
C. G. Nolte, K. W. Appel, J. T. Kelly, P. V. Bhave, K. M. Fahey, J. L. Collett, L. Zhang, J. O. Young |
| 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 ; 8, no. 9 ; Nr. 8, no. 9 (2015-09-15), S.2877-2892 |
| Datensatznummer |
250116558
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| Publikation (Nr.) |
 copernicus.org/gmd-8-2877-2015.pdf |
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| Zusammenfassung |
| This work evaluates particle size–composition distributions simulated
by the Community Multiscale Air Quality (CMAQ) model using
micro-orifice uniform deposit impactor (MOUDI) measurements at 18
sites across North America. Size-resolved measurements of particulate
SO42−, NO3−, NH4+, Na+,
Cl−, Mg2+, Ca2+, and K+ are
compared to CMAQ model output for discrete sampling periods between
2002 and 2005. The observation sites were predominantly in remote
areas (e.g., National Parks) in the USA and Canada, and
measurements were typically made for a period of roughly 1 month.
For SO42− and NH4+, model performance was
consistent across the USA and Canadian sites, with the model slightly
overestimating the peak particle diameter and underestimating the peak
particle concentration compared to the observations. Na+ and
Mg2+ size distributions were generally well represented at
coastal sites, indicating reasonable simulation of emissions from sea
spray. CMAQ is able to simulate the displacement of Cl− in
aged sea spray aerosol, though the extent of Cl− depletion
relative to Na+ is often underpredicted. The model
performance for NO3− exhibited much more site-to-site
variability than that of SO42− and NH4+, with the
model ranging from an underestimation to overestimation of both the
peak diameter and peak particle concentration across the
sites. Computing PM2.5 from the modeled size distribution
parameters rather than by summing the masses in the Aitken and
accumulation modes resulted in differences in daily averages of up to
1 μg m−3 (10 %), while the difference in seasonal
and annual model performance compared to observations from the
Interagency Monitoring of Protected Visual Environments (IMPROVE), Chemical Speciation Network (CSN), and
Air Quality System (AQS) networks was very small. Two updates to the CMAQ
aerosol model – changes to the assumed size and mode width of emitted
particles and the implementation of gravitational settling – resulted
in small improvements in modeled size distributions. |
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