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Proceedings Paper

Optimization of the mixing ratio of ice crystal shapes in cirrus clouds for atmospheric point spread function modeling
Author(s): Isabelle Muguet; Patrick Chervet; Claude Rozé
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Paper Abstract

A critical issue to calculate the image transmission through cirrus clouds is to obtain a detailed description of the angular distribution of the scattered radiation in the forward direction. Computation of the scattering phase function on the basis of microphysics description of the cloud thanks to ray-tracing codes, seems to be the best way to fulfill this requirement. However, a comprehensive microphysical model can not be found, because of the great variability of the ice crystals composing natural cirrus. An optimization process has been developed to find the best mixing ratio of four pristine ice crystals shapes that minimizes the error on the forward peak of the scattering phase function. To achieve this goal, a comparison with a reference phase function derived from MODIS database has been led. The bulk scattering properties of the seven size distributions defined in this database have been computed at four wavelengths in the spectral domain from visible to medium infrared, applying the mixing ratio obtained after an optimization at 0.55μm. Used as an input to a propagation model based on a Monte Carlo method, PSF have been computed. They show very good agreement with the PSF calculated with the corresponding reference scattering properties.

Paper Details

Date Published: 29 October 2007
PDF: 11 pages
Proc. SPIE 6747, Optics in Atmospheric Propagation and Adaptive Systems X, 67470E (29 October 2007); doi: 10.1117/12.737039
Show Author Affiliations
Isabelle Muguet, ONERA (France)
Univ. de Rouen (France)
Patrick Chervet, ONERA (France)
Claude Rozé, Univ. de Rouen (France)

Published in SPIE Proceedings Vol. 6747:
Optics in Atmospheric Propagation and Adaptive Systems X
Karin Stein; Anton Kohnle; John D. Gonglewski, Editor(s)

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