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| Titel |
Sensitivities of NOx transformation and the effects on surface ozone and nitrate |
| VerfasserIn |
H. Lei, J. X. L. Wang |
| 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 ; 14, no. 3 ; Nr. 14, no. 3 (2014-02-05), S.1385-1396 |
| Datensatznummer |
250118358
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| Publikation (Nr.) |
 copernicus.org/acp-14-1385-2014.pdf |
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| Zusammenfassung |
| As precursors to tropospheric ozone and nitrate, nitrogen oxide
(NOx) in the present atmosphere and its transformation in
response to emission and climate perturbations are studied by using the
CAM-Chem model and air quality measurements from the National Emissions
Inventory (NEI), Clean Air Status and Trends Network (CASTNET), and
Environmental Protection Agency Air Quality System (EPA AQS). It is found
that NOx transformations in present atmospheric conditions show
different sensitivities over industrial and non-industrial regions. As a
result, the surface ozone and nitrate formations can be divided into several
regimes associated with the dominant emission types and relative levels of
NOx and volatile organic compounds (VOC). Ozone production in industrial
regions (the main NOx emission source areas)
increases in warmer conditions and slightly decreases following an increase in
NOx emissions due to NOx titration, which is opposite
to the response in non-industrial regions. The ozone decrease following a
temperature increase in non-industrial regions indicates that ozone
production in regions that lack NOx emission sources may be
sensitive to NOx transformation in remote source regions. The
increase in NO2 from NOx titration over industrial regions
results in an increase rate of total nitrate that remains higher than the
increase
rate of NOx emissions. The presented findings indicate that a
change in the ozone concentration is more directly affected by changes in
climate and precursor emissions, while a change in the nitrate concentration
is affected by local ozone production types and their seasonal transfer. The
sensitivity to temperature perturbations shows that a warmer climate
accelerates the decomposition of odd nitrogen (NOy) during the
night. As a result, the transformation rate of NOx to nitrate
decreases. Examinations of the historical emissions and air quality records
of a typical NOx-limited area, such as Atlanta and a VOC-limited
area, such as Los Angeles further confirm the conclusions drawn from the modeling
experiments. |
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