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| Titel |
Observationally-constrained estimates of global fine-mode AOD |
| VerfasserIn |
K. Lee, C. E. Chung |
| 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 ; 13, no. 5 ; Nr. 13, no. 5 (2013-03-13), S.2907-2921 |
| Datensatznummer |
250018489
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| Publikation (Nr.) |
 copernicus.org/acp-13-2907-2013.pdf |
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| Zusammenfassung |
Small aerosols are mostly anthropogenic, and the fine-mode aerosol optical
depth (fAOD) can be used to infer anthropogenic aerosol amounts. We estimate
AOD and fAOD globally on a monthly time scale from 2001 to 2010 by
integrating monthly satellite-based (MODIS and MISR) and ground-based
(AERONET) observations. For fAOD, three integration methods are developed to
utilize global coverage by satellite data and maximize the influence of
AERONET data. We evaluate each method by applying the method without a few
randomly-chosen AERONET data and comparing its output with the few AERONET
data. The best method of the three is based on integrating the
Ångström exponent (AE) data from MODIS, MISR and AERONET, and its
output is closer to AERONET fAOD accuracy than MODIS or MISR fAOD over both
ocean and land.
Using our integrated data, we find that the global 2001–2010 average of 500 nm
AOD and fAOD is 0.17 and 0.089, respectively. Eastern China as a region
shows the largest decadal-mean fAOD. The linear trend of global AOD or
global fAOD from 2001 to 2010 is found to be slightly negative. This
decreasing trend is particularly pronounced over the West (Western Europe
and US/Canada combined) where AOD and fAOD reductions are about −20%. By
contrast, fAOD in India and eastern China combined increased slightly. These
results reflect the overall anthropogenic aerosol emission reduction in the
West, and stagnating conditions in Asia. Moreover, our results in the West
are consistent with the so-called surface brightening phenomenon in the
recent decades. |
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