“…In most of the previous studies employing the DDA to calculate scattering by atmospheric aerosols, parameterized models of particle geometry were developed, and the changes in the scattering properties of the particles as predicted by the DDA as a function of variations in the geometric parameters were investigated. This includes particles with an idealized geometry and mixing state [Kocifaj and Videen, 2008] and laboratorygenerated aerosols [Scarnato et al, 2013], as well as geometries and internal structures based on atmospheric particle observations [Chamaillard et al, 2006;Kocifaj et al, 2006;Worringen et al, 2008;Nousiainen et al, 2009;Adachi et al, 2010]. The results of DDA implementations that mimic specific internal mixing states of idealized particles (with mixed compositions of ammonium sulfate, organic matter, salts, and carbonaceous material) show both significant [Worringen et al, 2008;Adachi et al, 2010] and insignificant [Kocifaj et al, 2006] variations in extinction efficiency as a function of the different internal structures modeled.…”