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| Titel |
Scattering and absorption properties of near-surface aerosol over Gangetic–Himalayan region: the role of boundary-layer dynamics and long-range transport |
| VerfasserIn |
U. C. Dumka, D. G. Kaskaoutis, M. K. Srivastava, P. C. S. Devara |
| 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 ; 15, no. 3 ; Nr. 15, no. 3 (2015-02-13), S.1555-1572 |
| Datensatznummer |
250119408
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| Publikation (Nr.) |
 copernicus.org/acp-15-1555-2015.pdf |
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| Zusammenfassung |
| Light scattering and absorption properties of atmospheric aerosols are of
vital importance for evaluating their types, sources and radiative forcing.
This is of particular interest over the Gangetic–Himalayan (GH) region due
to uplift of aerosol from the plains to the Himalayan range, causing serious
effects on atmospheric heating, glaciology and monsoon circulation. In this
respect, the Ganges Valley Aerosol Experiment (GVAX) was initiated in Nainital
from June 2011 to March 2012 with the aim of examining the aerosol properties,
source regions, uplift mechanisms and aerosol–radiation–cloud interactions.
The present study examines the temporal (diurnal, monthly, seasonal)
evolution of scattering (σ) and absorption (σap)
coefficients, their wavelength dependence, and the role of the Indo-Gangetic
plains (IGP), boundary-layer dynamics (BLD) and long-range transport (LRT)
in aerosol evolution via the Atmospheric Radiation Measurement Mobile
Facility. The analysis is separated for particles <10 μm and
<1 μm in diameter in order to examine the influence of
particle size on optical properties. The σsp and σap exhibit a pronounced seasonal variation between the monsoon low and
post-monsoon (November) high, while the scattering wavelength exponent
exhibits higher values during the monsoon, in contrast to the absorption
Ångström exponent which maximizes in December–March. The
elevated-background measuring site provides the advantage of examining the
LRT of natural and anthropogenic aerosols from the IGP and southwest Asia
and the role of BLD in the aerosol lifting processes. The results reveal
higher aerosol concentrations at noontime along with an increase in mixing
height, suggesting influence from IGP. The locally emitted aerosols present
higher wavelength dependence of the absorption in October–March
compared to the rather well-mixed and aged transported aerosols.
Monsoon rainfall and seasonally changing air masses contribute to the
alteration of the extensive and intensive aerosol properties. |
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