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| Titel |
Multi-decadal aerosol variations from 1980 to 2009: a perspective from observations and a global model |
| VerfasserIn |
M. Chin, T. Diehl, Q. Tan, J. M. Prospero, R. A. Kahn, L. A. Remer, H. Yu, A. M. Sayer, H. Bian, I. V. Geogdzhayev, B. N. Holben, S. G. Howell, B. J. Huebert, N. C. Hsu, D. Kim, T. L. Kucsera, R. C. Levy, M. I. Mishchenko, X. Pan, P. K. Quinn, G. L. Schuster, D. G. Streets, S. A. Strode, O. Torres, X.-P. Zhao |
| 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. 7 ; Nr. 14, no. 7 (2014-04-10), S.3657-3690 |
| Datensatznummer |
250118580
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| Publikation (Nr.) |
 copernicus.org/acp-14-3657-2014.pdf |
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| Zusammenfassung |
| Aerosol variations and trends over different land and ocean regions from 1980
to 2009 are analyzed with the Goddard Chemistry Aerosol Radiation and
Transport (GOCART) model and observations from multiple satellite sensors and
available ground-based networks. Excluding time periods with large volcanic
influence, aerosol optical depth (AOD) and surface concentration over
polluted land regions generally vary with anthropogenic emissions, but the
magnitude of this association can be dampened by the presence of natural
aerosols, especially dust. Over the 30-year period in this study, the largest
reduction in aerosol levels occurs over Europe, where AOD has decreased by
40–60% on average and surface sulfate concentrations have declined by a
factor of up to 3–4. In contrast, East Asia and South Asia show AOD
increases, but the relatively high level of dust aerosols in Asia reduces the
correlation between AOD and pollutant emission trends. Over major dust source
regions, model analysis indicates that the change of dust emissions over the
Sahara and Sahel has been predominantly driven by the change of near-surface
wind speed, but over Central Asia it has been largely influenced by the
change of the surface wetness. The decreasing dust trend in the North African
dust outflow region of the tropical North Atlantic and the receptor sites of
Barbados and Miami is closely associated with an increase of the sea surface
temperature in the North Atlantic. This temperature increase may drive the
decrease of the wind velocity over North Africa, which reduces the dust
emission, and the increase of precipitation over the tropical North Atlantic,
which enhances dust removal during transport. Despite significant trends over
some major continental source regions, the model-calculated global annual
average AOD shows little change over land and ocean in the past three
decades, because opposite trends in different land regions cancel each other
out in the global average, and changes over large open oceans are negligible.
This highlights the necessity for regional-scale assessment of aerosols and
their climate impacts, as global-scale average values can obscure important
regional changes. |
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