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| Titel |
Trends in OMI NO2 observations over the United States: effects of emission control technology and the economic recession |
| VerfasserIn |
A. R. Russell, L. C. Valin, R. C. Cohen |
| 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. 24 ; Nr. 12, no. 24 (2012-12-21), S.12197-12209 |
| Datensatznummer |
250011687
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| Publikation (Nr.) |
 copernicus.org/acp-12-12197-2012.pdf |
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| Zusammenfassung |
| Observations of tropospheric NO2 vertical column densities over the
United States (US) for 2005–2011 are evaluated using the OMI Berkeley High
Resolution (BEHR) retrieval algorithm. We assess changes in NO2 on
day-of-week and interannual timescales to assess the impact of changes in
emissions from mobile and non-mobile sources on the observed trends. We
observe consistent decreases in cities across the US, with an average total
reduction of 32 ± 7% across the 7 yr. Changes for large power
plants have been more variable (−26 ± 12%) due to
regionally-specific regulation policies. An increasing trend of 10–20%
in background NO2 columns in the northwestern US is observed. We
examine the impact of the economic recession on emissions and find that
decreases in NO2 column densities over cities were moderate prior to
the recession (−6 ± 5% yr−1), larger during the recession
(−8 ± 5% yr−1), and then smaller after the recession (−3 ± 4% yr−1). Differences in the trends observed on weekdays
and weekends indicate that prior to the economic recession, NO2
reductions were dominated by technological improvements to the light-duty
vehicle fleet but that a decrease in diesel truck activity has contributed
to emission reductions since the recession. We use the satellite
observations to estimate a 34% decrease in NO2 from mobile sources
in cities for 2005–2011 and use that value to infer changes in non-mobile
sources. We find that reductions in NO2 from non-mobile sources in
cities have been both more modest and more variable than NO2 reductions
from mobile sources (−10 ± 13%). |
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