Abstract

Information about the size distribution of liquid droplets in a fog can be retrieved by measuring the backscattering lidar depolarization parameter D in circular polarization. Using a polarimetric off-axis lidar, measurements at different backscattering angles are performed on fogs made of water droplets and of mineral oil. Estimation of the effective droplet size is obtained using constrained linear inversion. Mie theory is used to calculate the variation in depolarization parameters for different effective droplet sizes. The calculation is performed for various scattering angles. These calculations provide a kernel for the constrained linear inversion scheme. It is shown that the refractive index has an effect on the retrieved droplet sizes as well as the choice of scattering angles. These measurements confirm that the circular depolarization parameter measured near the backscattering angle can be modeled as a function of the forward-scattering diffraction peak. The results of the constrained linear inversion of measurements are consistent with in situ measurement of the droplet size distribution.

© 2019 Optical Society of America

Scattering phase function depolarization parameter model and its application to water droplets sizing using off-axis lidar measurements at multiple angles

Gilles Roy, Gregoire Tremblay, and Xiaoying Cao
Appl. Opt. 57(4) 969-977 (2018)

Retrieval of droplet-size density distribution from multiple-field-of-view cross-polarized lidar signals: theory and experimental validation

Gilles Roy, Luc Bissonnette, Christian Bastille, and Gilles Vallée
Appl. Opt. 38(24) 5202-5211 (1999)

Comparison of the relationships between lidar integrated backscattered light and accumulated depolarization ratios for linear and circular polarization for water droplets, fog oil, and dust

Xiaoying Cao, Gilles Roy, Nathalie Roy, and Robert Bernier
Appl. Opt. 48(21) 4130-4141 (2009)

Relation between circular and linear depolarization ratios under multiple-scattering conditions

Gilles Roy and Nathalie Roy
Appl. Opt. 47(35) 6563-6579 (2008)

Polarimetric multiple scattering LiDAR model based on Poisson distribution

Gilles Roy and Grégoire Tremblay
Appl. Opt. 61(18) 5507-5516 (2022)