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| Titel |
Regional-scale transport of air pollutants: impacts of Southern California emissions on Phoenix ground-level ozone concentrations |
| VerfasserIn |
J. Li, M. Georgescu, P. Hyde, A. Mahalov, M. Moustaoui |
| 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 ; 15, no. 16 ; Nr. 15, no. 16 (2015-08-21), S.9345-9360 |
| Datensatznummer |
250119984
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| Publikation (Nr.) |
 copernicus.org/acp-15-9345-2015.pdf |
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| Zusammenfassung |
In this study, WRF-Chem is utilized at high resolution (1.333 km grid
spacing for the innermost domain) to investigate impacts of southern
California anthropogenic emissions (SoCal) on Phoenix ground-level ozone
concentrations ([O3]) for a pair of recent exceedance episodes. First,
WRF-Chem control simulations, based on the US Environmental Protection
Agency (EPA) 2005 National Emissions Inventories (NEI05), are conducted to
evaluate model performance. Compared with surface observations of hourly
ozone, CO, NOX, and wind fields, the control simulations reproduce
observed variability well. Simulated [O3] are comparable with the
previous studies in this region. Next, the relative contribution of SoCal
and Arizona local anthropogenic emissions (AZ) to ozone exceedances within
the Phoenix metropolitan area is investigated via a trio of sensitivity
simulations: (1) SoCal emissions are excluded, with all other emissions as
in Control; (2) AZ emissions are excluded with all other emissions as in
Control; and (3) SoCal and AZ emissions are excluded (i.e., all
anthropogenic emissions are eliminated) to account only for Biogenic
emissions and lateral boundary inflow (BILB). Based on the USEPA NEI05,
results for the selected events indicate the impacts of AZ emissions are
dominant on daily maximum 8 h average (DMA8) [O3] in Phoenix. SoCal
contributions to DMA8 [O3] for the Phoenix metropolitan area range from
a few ppbv to over 30 ppbv (10–30 % relative to Control experiments).
[O3] from SoCal and AZ emissions exhibit the expected diurnal
characteristics that are determined by physical and photochemical processes,
while BILB contributions to DMA8 [O3] in Phoenix also play a key role.
Finally, ozone transport processes and pathways within the lower troposphere
are investigated. During daytime, pollutants (mainly ozone) near the
Southern California coasts are pumped into the planetary boundary-layer over
the Southern California desert through the mountain chimney and pass channel
effects, aiding eastward transport along the desert air basins in southern
California and finally, northeastward along the lower Gila River basin in
Arizona, thereby affecting Phoenix air quality during subsequent days. This
study indicates that local emission controls in Phoenix need to be augmented
with regional emission reductions to attain the federal ozone standard,
especially if a more stringent standard is adopted in the future. |
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