Investigating particle orientation in cirrus clouds by measuring backscattering phase matrices with lidar

The relation between the orientation of particles in ice-crystal clouds and backscattering phase matrices (BSPMs) is considered. Parameters characterizing the predominant orientation of particles in the azimuthal direction and in the horizontal position are presented. The parameters are expressed th...

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Veröffentlicht in:Applied Optics 2004-12, Vol.43 (36), p.6620-6628
Hauptverfasser: Kaul, Bruno V, Samokhvalov, Ignatii V, Volkov, Sergei N
Format: Artikel
Sprache:eng
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Zusammenfassung:The relation between the orientation of particles in ice-crystal clouds and backscattering phase matrices (BSPMs) is considered. Parameters characterizing the predominant orientation of particles in the azimuthal direction and in the horizontal position are presented. The parameters are expressed through BSPM elements. A technique for measuring BSPM elements with lidar is described. Examples of some measurements are presented along with a statistical generalization of the results from more than 400 BSPM measurements. It is found that the orientation of coarse particles with large diameters in an azimuthal direction and in a horizontal position is more probable than in a random direction. However, the orientation of large particles is often masked by small particles that are not subject to the effect of orienting factors. Thus the mean parameters characterizing the state of orientation of particles in clouds as a whole correspond to weak orientation. It is supposed that the orientation of particles in the azimuthal direction is caused by wind-velocity pulsations.
ISSN:1559-128X
0003-6935
1539-4522
DOI:10.1364/AO.43.006620