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| Titel |
Cloud particle size distributions measured with an airborne digital in-line holographic instrument |
| VerfasserIn |
J. P. Fugal, R. A. Shaw |
| 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 ; 2, no. 1 ; Nr. 2, no. 1 (2009-06-17), S.259-271 |
| Datensatznummer |
250000442
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| Publikation (Nr.) |
 copernicus.org/amt-2-259-2009.pdf |
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| Zusammenfassung |
Holographic data from the prototype airborne digital holographic
instrument HOLODEC (Holographic Detector for Clouds), taken during
test flights are digitally reconstructed to obtain the size
(equivalent diameters in the range 23 to 1000 μm),
three-dimensional position, and two-dimensional image of ice
particles and then ice particle size distributions and number
densities are calculated using an automated algorithm with minimal
user intervention. The holographic method offers the advantages of a
well-defined sample volume size that is not dependent on particle
size or airspeed, and offers a unique method of detecting shattered
particles. The holographic method also allows the volume sample rate
to be increased beyond that of the prototype HOLODEC instrument,
limited solely by camera technology.
HOLODEC size distributions taken in mixed-phase regions of cloud
compare well to size distributions from a PMS FSSP probe also
onboard the aircraft during the test flights. A conservative
algorithm for detecting shattered particles utilizing their
depth-position along the optical axis eliminates the obvious ice
particle shattering events from the data set. In this particular
case, the size distributions of non-shattered particles are reduced
by approximately a factor of two for particles 15 to 70 μm in
equivalent diameter, compared to size distributions of all
particles. |
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