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| Titel |
Transport and mixing patterns over Central California during the carbonaceous aerosol and radiative effects study (CARES) |
| VerfasserIn |
J. D. Fast, W. I. Jr. Gustafson, L. K. Berg, W. J. Shaw, M. Pekour, M. Shrivastava, J. C. Barnard, R. A. Ferrare, C. A. Hostetler, J. A. Hair, M. Erickson, B. T. Jobson, B. Flowers, M. K. Dubey, S. Springston, R. B. Pierce, L. Dolislager, J. Pederson, R. A. Zaveri |
| 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 ; 12, no. 4 ; Nr. 12, no. 4 (2012-02-17), S.1759-1783 |
| Datensatznummer |
250010723
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| Publikation (Nr.) |
 copernicus.org/acp-12-1759-2012.pdf |
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| Zusammenfassung |
| We describe the synoptic and regional-scale meteorological conditions that
affected the transport and mixing of trace gases and aerosols in the
vicinity of Sacramento, California during June 2010 when the Carbonaceous
Aerosol and Radiative Effects Study (CARES) was conducted. The
meteorological measurements collected by various instruments deployed during
the campaign and the performance of the chemistry version of the Weather
Research and Forecasting model (WRF-Chem) are both discussed. WRF-Chem was
run daily during the campaign to forecast the spatial and temporal variation
of carbon monoxide emitted from 20 anthropogenic source regions in
California to guide aircraft sampling. The model is shown to reproduce the
overall circulations and boundary-layer characteristics in the region,
although errors in the upslope wind speed and boundary-layer depth
contribute to differences in the observed and simulated carbon monoxide.
Thermally-driven upslope flows that transported pollutants from Sacramento
over the foothills of the Sierra Nevada occurred every afternoon, except
during three periods when the passage of mid-tropospheric troughs disrupted
the regional-scale flow patterns. The meteorological conditions after the
passage of the third trough were the most favorable for photochemistry and
likely formation of secondary organic aerosols. Meteorological measurements
and model forecasts indicate that the Sacramento pollutant plume was likely
transported over a downwind site that collected trace gas and aerosol
measurements during 23 time periods; however, direct transport occurred
during only eight of these periods. The model also showed that emissions
from the San Francisco Bay area transported by intrusions of marine air
contributed a large fraction of the carbon monoxide in the vicinity of
Sacramento, suggesting that this source likely affects local chemistry.
Contributions from other sources of pollutants, such as those in the
Sacramento Valley and San Joaquin Valley, were relatively low. Aerosol
layering in the free troposphere was observed during the morning by an
airborne Lidar. WRF-Chem forecasts showed that mountain venting processes
contributed to aged pollutants aloft in the valley atmosphere that are then
entrained into the growing boundary layer the subsequent day. |
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