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Titel |
A new method for measuring optical scattering properties of atmospherically relevant dusts using the Cloud and Aerosol Spectrometer with Polarization (CASPOL) |
VerfasserIn |
A. Glen, S. D. Brooks |
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 ; 13, no. 3 ; Nr. 13, no. 3 (2013-02-01), S.1345-1356 |
Datensatznummer |
250017633
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Publikation (Nr.) |
copernicus.org/acp-13-1345-2013.pdf |
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Zusammenfassung |
Atmospheric aerosols have major impacts on regional and global climate
through scattering and absorption of solar radiation. A new instrument, the
Cloud and Aerosol Spectrometer with Polarization (CASPOL) from Droplet
Measurement Technologies measures light scattered by aerosols in the forward
(4° to 12°) and backward (168° to 176°)
directions, with an additional polarized detector in the
backward direction. Scattering by a single particle can be measured by all
three detectors for aerosols in a broad range of sizes, 0.6 μm
< diameter < 50 μm. The CASPOL is a unique
measurement tool, since unlike most in-situ probes, it can measure optical
properties on a particle-by-particle basis. In this study, single particle
CASPOL measurements for thirteen atmospherically relevant dusts were
obtained and their optical scattering signatures were evaluated. In
addition, Scanning Electron Microscopy (SEM) was used to characterize the
shape and morphology of each type of dust. The total and polarized
backscatter intensities varied with particle size for all dust types. Using
a new optical signature technique all but one dust type could be categorized
into one of three optical scattering groups. Additionally, a composite
method was used to derive the optical signature of Arizona Test Dust (ATD)
by combining the signatures of its major components. The derived signature
was consistent with the measured signature of ATD. Finally, calculated
backscattering cross sections for representative dust from each of the three
main groups were found to vary by as much as a factor of 7, the difference
between the backscattering cross sections of white quartz (5.3 × 10−10 cm−2)
and hematite (4.1 × 10−9 cm−2). |
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