Demonstration of Sensitivity of Backscattering to Spherical Particle Physical Properties: Size, Refractive Index, and Shape Deviations

PRAKASH GAUTAM, Hans Moosmüller, Christopher M. Sorensen, Justin Maughan, Desert Research Institute

     Abstract Number: 228
     Working Group: Coast to Coast Campaigns on Aerosols, Clouds, Chemistry, and Air Quality

Abstract
Backscattering of light by spherical particles is greatly affected by the small change in particle physical properties: size, refractive index, and shape deviations. We present how the non-descriptive backscattering pattern evolves compared to the comprehensible forward scattering, depending on the particle’s physical properties. The demonstration is carried out by changing the physical properties of spherical particles by ± 2.5% and analyzing the same data using two analysis methods: vs. the linear scattering angle, θ–space and logarithmically when plotting them vs. the magnitude of the scattering wave vector q, called Q–space analysis. The results showed systematic, descriptive evolution of the forward scattering pattern, which is clearly shown in logarithmic Q–space, whereas non-descriptive, seemingly chaotic evolution within the backscattering regime, as displayed in linear θ–space. This study emphasizes that while Mie’s theory provides accurate light scattering results for spherical particles, interpretation of measured backscattering data requires accurate characterization of particle physical properties. Overall, the results offer practical value to those engaged in particle scattering and to professionals within the lidar and remote sensing communities.