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

Abstract

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.

Depolarization calibration and measurements using the CANDAC Rayleigh–Mie–Raman lidar at Eureka, Canada

“…The recent papers on depolarization calibration are moving away from a scalar description, and are moving toward a vector description of light, with matrix algebra describing the optical effects of the sky (Kaul et al, 2004;Hayman and Thayer, 2009, using Mueller matrix algebra) and of the lidar itself (Biele et al, 2000;Thayer, 2009, 2012;Neely III et al, 2013;Freudenthaler, 2016, using Mueller matrix algebra andBu et al, 2017, using Jones matrices).…”

First Look at the Occurrence of Horizontally Oriented Ice Crystals over Summit, Greenland

“…Only recent advancements in polarimetric active remote sensing have allowed for HOIC to be unambiguously 25 (i.e. measuring a property exhibited solely by HOIC) identified with a single instrument (Kaul et al 2004;Neely et al, 2013;Hayman and Thayer, 2012;Hayman et al 2012). Neely et al (2013) utilize Atmos.…”

Problem of data interpretation of laser polarization sensing of high-level clouds on the basis of theoretically calculated phase matrices of backscattering by monodisperse ice crystals

“…Thus, to evaluate the microstructure parameters of the cloud, it is necessary to determine its BSPM. To investigate special features of cirrus clouds, polarization laser sensing method [1] is used in the high-altitude polarization lidar developer at National Research Tomsk State University (TSU; Tomsk, Russia) [2]. Transmission system of the lidar sends radiation with 4 various polarization states, which are described by the Stokes vector S n (n takes values from 1 to 4) into the atmosphere.…”