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| Titel |
Trend analysis of aerosol optical thickness and Ångström exponent derived from the global AERONET spectral observations |
| VerfasserIn |
J. Yoon, W. Hoyningen-Huene, A. A. Kokhanovsky, M. Vountas, J. P. Burrows |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1867-1381
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| Digitales Dokument |
URL |
| Erschienen |
In: Atmospheric Measurement Techniques ; 5, no. 6 ; Nr. 5, no. 6 (2012-06-06), S.1271-1299 |
| Datensatznummer |
250002965
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| Publikation (Nr.) |
 copernicus.org/amt-5-1271-2012.pdf |
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| Zusammenfassung |
Regular aerosol observations based on well-calibrated instruments have led
to a better understanding of the aerosol radiative budget on Earth. In
recent years, these instruments have played an important role in the
determination of the increase of anthropogenic aerosols by means of
long-term studies. Only few investigations regarding long-term trends of
aerosol optical characteristics (e.g. aerosol optical thickness (AOT) and
Ångström exponent (ÅE)) have been derived from ground-based
observations. This paper aims to derive and discuss linear trends of AOT
(440, 675, 870, and 1020 nm) and ÅE (440–870 nm) using AErosol RObotic
NETwork (AERONET) level 2.0 spectral observations. Additionally, temporal
trends of coarse- and fine-mode dominant AOTs (CdAOT and FdAOT) have been
estimated by applying an aerosol classification based on accurate ÅE and
Ångström exponent difference (ÅED). In order to take into
account the fact that cloud disturbance is having a significant influence on
the trend analysis of aerosols, we introduce a weighted least squares
regression depending on two weights: (1) monthly standard deviation
(σt) and (2) number of observations per month (nt).
Temporal increase of FdAOTs (440 nm) prevails over newly industrializing
countries in East Asia (weighted trends; +6.23% yr−1 at Beijing) and
active agricultural burning regions in South Africa (+1.89% yr−1 at
Mongu). On the other hand, insignificant or negative trends for FdAOTs are
detected over Western Europe (+0.25% yr−1 at Avignon and
−2.29% yr−1 at Ispra) and North America (−0.52% yr−1 for GSFC and
−0.01% yr−1 at MD_Science_Center). Over desert regions, both
increase and decrease of CdAOTs (+3.37% yr−1 at Solar_Village and
−1.18% yr−1 at Ouagadougou) are observed depending on meteorological
conditions. |
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