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| Titel |
A two-habit model for the microphysical and optical properties of ice clouds |
| VerfasserIn |
C. Liu, P. Yang, P. Minnis, N. Loeb, S. Kato, A. Heymsfield, C. Schmitt |
| 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 ; 14, no. 24 ; Nr. 14, no. 24 (2014-12-22), S.13719-13737 |
| Datensatznummer |
250119262
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| Publikation (Nr.) |
 copernicus.org/acp-14-13719-2014.pdf |
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| Zusammenfassung |
| To provide a better representation of natural ice clouds, a novel ice cloud
model is developed by assuming an ice cloud to consist of an ensemble of
hexagonal columns and 20-element aggregates with specific habit
fractions at each particle size bin. The microphysical and optical
properties of this two-habit model (THM) are compared with both laboratory
and in situ measurements, and its performance in downstream satellite remote
sensing applications is assessed. The ice water contents and median mass
diameters calculated based on the THM closely agree with in situ
measurements made during 11 field campaigns. In this study, the scattering,
absorption, and polarization properties of ice crystals are calculated with
a combination of the invariant imbedding T matrix, pseudo-spectral time
domain, and improved geometric-optics methods over an entire practical range
of particle sizes. The phase functions, calculated based on the THM, show
close agreement with counterparts from laboratory and in situ measurements
and from satellite-based retrievals. When the THM is applied to the
retrievals of cloud microphysical and optical properties from MODIS (the Moderate Resolution Imaging
Spectroradiometer) observations, excellent spectral consistency is achieved; specifically, the
retrieved cloud optical thicknesses based on the visible/near infrared bands
and the thermal infrared bands agree quite well. Furthermore, a comparison
between the polarized reflectivities observed by the PARASOL satellite and
from theoretical simulations illustrates that the THM can be used to
represent ice cloud polarization properties. |
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