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| Titel |
Light scattering at small angles by atmospheric irregular particles: modelling and laboratory measurements |
| VerfasserIn |
T. Lurton, J.-B. Renard, D. Vignelles, M. Jeannot, R. Akiki, J.-L. Mineau, T. Tonnelier |
| 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 ; 7, no. 4 ; Nr. 7, no. 4 (2014-04-07), S.931-939 |
| Datensatznummer |
250115692
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| Publikation (Nr.) |
 copernicus.org/amt-7-931-2014.pdf |
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| Zusammenfassung |
We have investigated the behaviour of light scattering by particulates of
various sizes (0.1 μm to 100 μm) at a
small scattering angle (below 20°). It has been previously
shown that, for a small angle, the scattered intensities are weakly dependent
upon the particulates' composition (Renard
et al., 2010). Particles found in the
atmosphere exhibit roughness that leads to large discrepancies with the
classical Mie solution in terms of scattered intensities in the low angular
set-up. This article focuses on building an effective theoretical tool to
predict the behaviour of light scattering by real particulates at a small
scattering angle.
We present both the classical Mie theory and its adaptation to the case of
rough particulates with a fairly simple roughness parameterisation. An
experimental device was built, corresponding to the angular set-up of
interest (low scattering angle and therefore low angular aperture).
Measurements are presented that confirm the theoretical results with good
agreement. It was found that differences between the classical Mie solution
and actual measurements – especially for large particulates – can be
attributed to the particulate roughness.
It was also found that, in this low angular set-up, saturation of the
scattered intensities occurs for relatively small values of the roughness
parameter. This confirms the low variability in the scattered intensities
observed for atmospheric particulates of different kinds.
A direct interest of this study is a broadening of the dynamic range of
optical counters: using a small angle of aperture for measurements allows
greater dynamics in terms of particle size. Thus it allows a single device to
observe a broad range of particle sizes whilst utilising the same
electronics. |
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