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| Titel |
The effect of meteorological and chemical factors on the agreement between observations and predictions of fine aerosol composition in southwestern Ontario during BAQS-Met |
| VerfasserIn |
M. Z. Markovic, K. L. Hayden, J. G. Murphy, P. A. Makar, R. A. Ellis, R. Y.-W. Chang, J. G. Slowik, C. Mihele, J. Brook |
| 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 ; 11, no. 7 ; Nr. 11, no. 7 (2011-04-05), S.3195-3210 |
| Datensatznummer |
250009587
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| Publikation (Nr.) |
 copernicus.org/acp-11-3195-2011.pdf |
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| Zusammenfassung |
| The Border Air Quality and Meteorology Study (BAQS-Met) was an intensive,
collaborative field campaign during the summer of 2007 that investigated the
effects of transboundary pollution, local pollution, and local meteorology
on air quality in southwestern Ontario. This analysis focuses on the
measurements of the inorganic constituents of particulate matter with
diameter of less than 1 μm (PM1), with a specific emphasis on
nitrate. We evaluate the ability of AURAMS, Environment Canada's chemical
transport model, to represent regional air pollution in SW Ontario by
comparing modelled aerosol inorganic chemical composition with measurements
from Aerosol Mass Spectrometers (AMS) onboard the National Research Council
(NRC) of Canada Twin Otter aircraft and at a ground site in Harrow, ON. The
agreement between modelled and measured pNO3− at the ground
site (observed mean (Mobs) = 0.50 μg m−3; modelled mean
(Mmod) = 0.58 μg m−3; root mean square error (RSME) = 1.27 μg m−3)
was better than aloft (Mobs = 0.32 μg m−3;
Mmod = 0.09 μg m−3; RSME = 0.48 μg m−3). Possible
reasons for discrepancies include errors in (i) emission inventories, (ii) atmospheric chemistry, (iii) predicted meteorological
parameters, or (iv) gas/particle thermodynamics in the model framework. Using the inorganic
thermodynamics model, ISORROPIA, in an offline mode, we find that the
assumption of thermodynamic equilibrium is consistent with observations of
gas and particle composition at Harrow. We develop a framework to assess the
sensitivity of PM1 nitrate to meteorological and chemical parameters
and find that errors in both the predictions of relative humidity and free
ammonia (FA ≡ NH3(g) + pNH4+ − 2 · pSO42-)
are responsible for the poor agreement between modelled and measured values. |
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