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| Titel |
Microwave single-scattering properties of randomly oriented soft-ice hydrometeors |
| VerfasserIn |
D. Casella, A. Mugnai, P. Sanò, M. Formenton |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1680-7340
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| Digitales Dokument |
URL |
| Erschienen |
In: 9th EGU Plinius Conference on Mediterranean Storms (2007) ; Nr. 17 (2008-11-14), S.79-85 |
| Datensatznummer |
250013628
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| Publikation (Nr.) |
 copernicus.org/adgeo-17-79-2008.pdf |
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| Zusammenfassung |
Large ice hydrometeors are usually present in intense convective clouds and
may significantly affect the upwelling radiances that are measured by
satellite-borne microwave radiometers – especially, at
millimeter-wavelength frequencies. Thus, interpretation of these
measurements (e.g., for precipitation retrieval) requires knowledge of the
single scattering properties of ice particles. On the other hand, shape and
internal structure of these particles (especially, the larger ones) is very
complex and variable, and therefore it is necessary to resort to simplifying
assumptions in order to compute their single-scattering parameters.
In this study, we use the discrete dipole approximation (DDA) to compute the
absorption and scattering efficiencies and the asymmetry factor of two kinds
of quasi-spherical and non-homogeneous soft-ice particles in the frequency
range 50–183 GHz. Particles of the first kind are modeled as
quasi-spherical ice particles having randomly distributed spherical air
inclusions. Particles of the second kind are modeled as random aggregates of
ice spheres having random radii. In both cases, particle densities and
dimensions are coherent with the snow hydrometeor category that is utilized
by the University of Wisconsin – Non-hydrostatic Modeling System (UW-NMS)
cloud-mesoscale model. Then, we compare our single-scattering results for
randomly-oriented soft-ice hydrometeors with corresponding ones that make
use of: a) effective-medium equivalent spheres, b) solid-ice equivalent
spheres, and c) randomly-oriented aggregates of ice cylinders. Finally, we
extend to our particles the scattering formulas that have been developed by
other authors for randomly-oriented aggregates of ice cylinders. |
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