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| Titel |
Impact of particle shape on the morphology of noctilucent clouds |
| VerfasserIn |
J. Kiliani, G. Baumgarten, F.-J. Lübken, U. Berger |
| 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. 22 ; Nr. 15, no. 22 (2015-11-19), S.12897-12907 |
| Datensatznummer |
250120174
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| Publikation (Nr.) |
 copernicus.org/acp-15-12897-2015.pdf |
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| Zusammenfassung |
| Noctilucent clouds (NLCs) occur during summer in the polar region at
altitudes around 83 km. They consist of ice particles with
a typical size around 50 nm. The shape of NLC particles is
less well known but is important both for interpreting optical
measurements and modeling ice cloud characteristics. In this paper,
NLC modeling of microphysics and optics is adapted to use
cylindrical instead of spherical
particle shape. The optical properties of the resulting ice clouds are
compared directly to NLC three-color measurements by the Arctic Lidar Observatory for Middle Atmosphere Research (ALOMAR) Rayleigh/Mie/Raman (RMR) lidar
between 1998 and 2014. Shape distributions including both needle- and
disc-shaped particles are consistent with lidar measurements. The best
agreement occurs if disc shapes are 60 % more common than
needles, with a mean axis ratio of 2.8. Cylindrical particles cause
stronger ice clouds on average than spherical shapes with an
increase of backscatter at 532 nm by ≈ 30 % and about 20 % in ice mass density.
This difference is less pronounced for bright than for
weak ice clouds. Cylindrical shapes also cause NLCs to have larger but
a smaller number of ice particles than for spherical shapes. |
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