AAAR 35th Annual Conference October 17 - October 21, 2016 Oregon Convention Center Portland, Oregon, USA
Abstract View
The Partial Scattering Cross Section and Efficiency
JUSTIN MAUGHAN, Chris Sorensen, Amit Chakrabarti, Kansas State University
Abstract Number: 468 Working Group: Aerosols, Clouds, and Climate
Abstract The partial scattering cross-section and efficiency are introduced. We define the partial scattering cross-section as integral of the differential scattering cross-section over theta from 0 to theta$_p and from 0 to 2pi over phi, where theta is the standard polar scattering angle and phi is the azimuthal angle. The partial efficiency is defined as the partial scattering cross-section normalized by the geometric cross-section of the particle as viewed from the direction of the incident light. Investigation of the partial scattering cross-section of a sphere shows that nearly half of all the scattered light is reached by theta$_p = lambda/3R where lambda is the wavelength of light and R is the radius of the sphere. Q-space analysis is applied to the partial scattering cross-section, which involves plotting vs. the scattering wave vector q = 2kRsin(theta/2) here k = 2pi/lambda on a log-log plot. When Q-space analysis is applied to the partial scattering cross-section, it is found that half of the scattered light comes from 2d diffraction while the other half comes from 3d diffraction. The internal coupling parameter rho'=2kR|(m$^2-1)/(m$^2+2)| provides a universal description of the partial quantities. When Q-space analysis is applied to the partial efficiency, it is found that strong absorption removes approximately one geometric cross-section from the scattered light. The removed geometric cross-section comes almost entirely from the 3d diffraction while leaving the 2d diffraction relatively unaffected.