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| Titel |
Long-term record of aerosol optical properties and chemical composition from a high-altitude site (Manora Peak) in Central Himalaya |
| VerfasserIn |
K. Ram, M. M. Sarin, P. Hegde |
| 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 ; 10, no. 23 ; Nr. 10, no. 23 (2010-12-13), S.11791-11803 |
| Datensatznummer |
250008953
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| Publikation (Nr.) |
 copernicus.org/acp-10-11791-2010.pdf |
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| Zusammenfassung |
| A long-term study, conducted from February 2005 to July 2008, involving chemical
composition and optical properties of ambient aerosols from a high-altitude
site (Manora Peak: 29.4° N, 79.5° E, ~1950 m a.s.l.) in the
central Himalaya is reported here. The total suspended particulate (TSP)
mass concentration varied from 13 to 272 μg m−3 over a span of 42
months. Aerosol optical depth (AOD) and TSP increase significantly during
the summer (April–June) due to increase in the concentration of mineral dust
associated with the long-range transport from desert regions (from the
middle-East and Thar Desert in western India). The seasonal variability in
the carbonaceous species (EC, OC) is also significantly pronounced, with
lower concentrations during the summer and monsoon (July–August) and
relatively high during the post-monsoon (September–November) and winter
(December–March). On average, total carbonaceous aerosols (TCA) and
water-soluble inorganic species (WSIS) contribute nearly 25 and 10% of
the TSP mass, respectively. The WSOC/OC ratios range from 0.36 to 0.83
(average: 0.55 ± 0.15), compared to lower ratios in the Indo-Gangetic
Plain (range: 0.35–0.40), and provide evidence for the enhanced
contribution from secondary organic aerosols. The mass fraction of absorbing
EC ranged from less than a percent (during the summer) to as high as 7.6%
(during the winter) and absorption coefficient (babs, at 678 nm) varied
between 0.9 to 33.9 Mm−1 (1 Mm−1=10−6 m−1). A significant
linear relationship between babs and EC (μgC m−3) yields a
slope of 12.2 (± 2.3) m2 g−1, which is used as a measure of
the mass absorption efficiency (σabs) of EC. |
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