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| Titel |
Retrieval of subvisual cirrus cloud optical thickness from limb-scatter measurements |
| VerfasserIn |
J. T. Wiensz, D. A. Degenstein, N. D. Lloyd, A. E. Bourassa |
| 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 ; 6, no. 1 ; Nr. 6, no. 1 (2013-01-22), S.105-119 |
| Datensatznummer |
250017375
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| Publikation (Nr.) |
 copernicus.org/amt-6-105-2013.pdf |
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| Zusammenfassung |
| We present a technique for estimating the optical thickness of subvisual
cirrus clouds detected by OSIRIS (Optical Spectrograph and Infrared Imaging System), a limb-viewing satellite instrument that
measures scattered radiances from the UV to the near-IR. The measurement set
is composed of a ratio of limb radiance profiles at two wavelengths that
indicates the presence of cloud-scattering regions. Cross-sections and phase
functions from an in situ database are used to simulate scattering by
cloud-particles. With appropriate configurations discussed in this paper, the
SASKTRAN successive-orders of scatter radiative transfer model is able to
simulate accurately the in-cloud radiances from OSIRIS. Configured in this
way, the model is used with a multiplicative algebraic reconstruction
technique (MART) to retrieve the cloud extinction profile for an assumed
effective cloud particle size. The sensitivity of these retrievals to key
auxiliary model parameters is shown, and it is shown that the retrieved
extinction profile, for an assumed effective cloud particle size, models well
the measured in-cloud radiances from OSIRIS. The greatest sensitivity of the
retrieved optical thickness is to the effective cloud particle size. Since
OSIRIS has an 11-yr record of subvisual cirrus cloud detections, the work
described in this manuscript provides a very useful method for providing a
long-term global record of the properties of these clouds. |
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