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| Titel |
Microphysical and optical properties of precipitating drizzle and ice particles obtained from alternated lidar and in situ measurements |
| VerfasserIn |
J.-F. Gayet, I. S. Stachlewska, O. Jourdan, V. Shcherbakov, A. Schwarzenboeck, R. Neuber |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
0992-7689
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| Digitales Dokument |
URL |
| Erschienen |
In: Annales Geophysicae ; 25, no. 7 ; Nr. 25, no. 7 (2007-07-30), S.1487-1497 |
| Datensatznummer |
250015873
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| Publikation (Nr.) |
 copernicus.org/angeo-25-1487-2007.pdf |
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| Zusammenfassung |
| During the international ASTAR experiment (Arctic Study
of Aerosols, Clouds and Radiation) carried out from Longyearbyen
(Spitsbergen) from 10 May to 11 June 2004, the AWI (Alfred Wegener
Institute) Polar 2 aircraft was equipped with a unique combination of remote
and in situ instruments. The airborne AMALi lidar provided downward
backscatter and Depolarisation ratio profiles at 532 nm wavelength. The in
situ instrumental setup comprised a Polar Nephelometer, a Cloud Particle
Imager (CPI) as well as a Nevzorov and standard PMS probes to measure cloud
particle properties in terms of scattering characteristics, particle
morphology and size, and in-cloud partitioning of ice/water content. The
objective of the paper is to present the results of a case study related to
observations with ice crystals precipitating down to supercooled
boundary-layer stratocumulus. The flight pattern was predefined in a way
that firstly the AMALi lidar probed the cloud tops to guide the in situ
measurements into a particular cloud formation. Three kinds of clouds with
different microphysical and optical properties have therefore been
quasi-simultaneously observed: (i) water droplets stratiform-layer, (ii)
drizzle-drops fallstreak and (iii) precipitating ice-crystals from a cirrus
cloud above. The signatures of these clouds are clearly evidenced from the
in situ measurements and from the lidar profiles in term of backscatter and
Depolarisation ratio. Accordingly, typical lidar ratios, i.e.,
extinction-to-backscatter ratios, are derived from the measured scattering
phase function combined with subsequent particle shapes and size
distributions. The backscatter profiles can therefore be retrieved under
favourable conditions of low optical density. From these profiles extinction
values in different cloud types can be obtained and compared with the direct
in situ measurements. |
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