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| Titel |
Improving Langley calibrations by reducing diurnal variations of aerosol Ångström parameters |
| VerfasserIn |
A. Kreuter, S. Wuttke, M. Blumthaler |
| 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 ; 6, no. 1 ; Nr. 6, no. 1 (2013-01-14), S.99-103 |
| Datensatznummer |
250017374
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| Publikation (Nr.) |
 copernicus.org/amt-6-99-2013.pdf |
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| Zusammenfassung |
| Errors in the sun photometer calibration constant lead to artificial diurnal
variations, symmetric around solar noon, of the retrieved aerosol optical
depth (AOD) and the associated Ångström exponent α and its curvature
γ. We show in simulations that within the uncertainty of
state-of-the-art Langley calibrations, these diurnal variations of α
and γ can be significant in low AOD conditions, while those of AOD
are negligible. We implement a weighted Monte Carlo method of finding an
improved calibration constant by minimizing the diurnal variations in
α and γ and apply the method to sun photometer data of a
clear day in Innsbruck, Austria. The results show that our method can be
used to improve the calibrations in two of the four wavelength channels by
up to a factor of 3.6. |
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