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| Titel |
Aircraft study of the impact of lake-breeze circulations on trace gases and particles during BAQS-Met 2007 |
| VerfasserIn |
K. L. Hayden, D. M. L. Sills, J. R. Brook, S.-M. Li, P. A. Makar, M. Z. Markovic, P. Liu, K. G. Anlauf, J. M. O'Brien, Q. Li, R. McLaren |
| 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. 19 ; Nr. 11, no. 19 (2011-10-10), S.10173-10192 |
| Datensatznummer |
250010119
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| Publikation (Nr.) |
 copernicus.org/acp-11-10173-2011.pdf |
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| Zusammenfassung |
| High time-resolved aircraft data, concurrent surface measurements and air
quality model simulations were explored to diagnose the processes
influencing aerosol chemistry under the influence of lake-breeze
circulations in a polluted region of southwestern Ontario, Canada. The
analysis was based upon horizontal aircraft transects conducted at multiple
altitudes across an entire lake-breeze circulation. Air mass boundaries due
to lake-breeze fronts were identified in the aircraft meteorological and
chemical data, which were consistent with the frontal locations determined
from surface analyses. Observations and modelling support the interpretation
of a lake-breeze circulation where pollutants were lofted at a lake-breeze
front, transported in the synoptic flow, caught in a downdraft over the
lake, and then confined by onshore flow. The detailed analysis led to the
development of conceptual models that summarize the complex 3-D circulation
patterns and their interaction with the synoptic flow. The identified air
mass boundaries, the interpretation of the lake-breeze circulation, and the air
parcel circulation time in the lake-breeze circulation (3.0 to 5.0 h)
enabled formation rates of organic aerosol (OA/ΔCO) and
SO42− to be determined. The formation rate for OA (relative to
excess CO in ppmv) was found to be
11.6–19.4 μg m−3 ppmv−1 h−1 and the SO42−
formation rate was 5.0–8.8% h−1.
The formation rates are enhanced relative to regional background rates
implying that lake-breeze circulations are an important dynamic in the
formation of SO42− and secondary organic aerosol. The presence of
cumulus clouds associated with the lake-breeze fronts suggests that these
enhancements could be due to cloud processes. Additionally, the effective
confinement of pollutants along the shoreline may have limited pollutant
dilution leading to elevated oxidant concentrations. |
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