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| Titel |
Retrieval of atmospheric optical parameters from ground-based sun-photometer measurements for Zanjan, Iran |
| VerfasserIn |
A. Bayat, A. Masoumi, H. R. Khalesifard |
| 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 ; 4, no. 5 ; Nr. 4, no. 5 (2011-05-11), S.857-863 |
| Datensatznummer |
250001979
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| Publikation (Nr.) |
 copernicus.org/amt-4-857-2011.pdf |
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| Zusammenfassung |
| We are reporting the results of ground-based spectroradiometric measurements
on aerosols and water vapor in the atmosphere of Zanjan for the period of
October 2006 to September 2008 using a CIMEL CE318-2 sun-photometer. Zanjan
is a city in Northwest Iran, located at 36.70° N, 48.51° E,
and at an altitude of 1800 m a.m.s.l. (above mean sea level). The spectral
aerosol optical depth, Ångström exponent, and columnar water vapor
have been calculated using the data recorded by the sun-photometer through
the direct measurements on the sun radiance (sun-mode). The average values of
aerosol optical depth at 440 nm, columnar water vapor, and the
Ångström exponent, α, during the mentioned period are measured
as, 0.28 ± 0.14, 0.57 ± 0.37 cm and 0.73 ± 0.30,
respectively. The maximum (minimum) value of the aerosol optical depth was
recorded in May 2007 (November 2007), and that of columnar water vapor, in
July 2007 (January 2008). Using the least-squares method, the
Ångström exponent was calculated in the spectral interval
440–870 nm along with α1 and α2, the coefficients of a
second order polynomial fit to the plotted logarithm of aerosol optical depth
versus the logarithm of wavelength. The coefficient α2 shows that
most of the aerosols in the Zanjan area have dimensions larger than
1 micron. The calculated values for α2 − α1 indicate that
80 % of the aerosols are in the coarse-mode (>1 μm) and 20 %
of them are in the fine-mode (<1 μm). Comparison of
α2 − α1 for the atmosphere over Zanjan with other regions
indicates dust particles are the most dominant aerosols in the region. |
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