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- Title
The effect of meteorological and chemical factors on the agreemen between observations and predictions of fine aerosol composition in southwestern Ontario during BAQS-Met.
- Authors
Markovic, M. Z.; Hayden, K. L.; Murphy, J. G.; Makar, P. A.; Ellis, R. A.; Chang, R. Y.-W.; Slowik, J. G.; Mihele, C.; Brook, J.
- Abstract
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 pNO Due to image rights restrictions, multiple line equation(s) cannot be graphically displayed. at the ground site (observed mean (Mobs) = 0.50μgm-3; modelled mean (Mmcva)=0.58 μgm-3; root mean square error (RSME)= 1.27 μgm was better than aloft (Mobs = 0.32 μ.gm-3; Mmod =0.09μgm-3; RSME=0.48p, μm-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) + Due to image rights restrictions, multiple line equation(s) cannot be graphically displayed.) are responsible for the poor agreement between modelled and measured values.
- Subjects
UNITED States; ATMOSPHERIC aerosols; AIR quality; ATMOSPHERIC chemistry; PARTICULATE matter; GEOCHEMISTRY; THERMODYNAMIC equilibrium; METEOROLOGY education; NATIONAL Research Council (U.S.)
- Publication
Atmospheric Chemistry & Physics, 2011, Vol 11, Issue 7, p3195
- ISSN
1680-7316
- Publication type
Article
- DOI
10.5194/acp-11-3195-2011