Light scattering by particles with small-scale surface roughness: comparison of four classes of model geometries
Journal article, 2012

We compare four different model geometries for particles with small-scale surface roughness. The geometries are based on regular and stochastic surface perturbations, as well as on 2D- and 3D-roughness models. We further compare T-matrix and discrete dipole computations. Particle size parameters of 5 and 50 are considered, as well as refractive indices of 1.6 + 0.0005i and 3 +0.1i. The effect of small-scale surface roughness on the intensity and polarisation of the scattered light strongly depends on the size parameter and refractive index. In general, 2D surface roughness models predict stronger effects than 3D models. Stochastic surface roughness models tend to predict the strongest depolarising effects, while regular surface roughness models can have a stronger effect on the angular distribution of the scattered intensity. Computations with the discrete dipole approximation only cover a limited range of size parameters. T-matrix computations allow us to significantly extend that range, but at the price of restricting the model particles to symmetric surface perturbations with small amplitudes.


Surface roughness




Mineral dust


Michael Kahnert

Chalmers, Earth and Space Sciences, Global Environmental Measurements and Modelling

T. Nousiainen

University of Helsinki

Manu Anna Thomas


Jani Tyynelä

University of Helsinki

Journal of Quantitative Spectroscopy and Radiative Transfer

0022-4073 (ISSN)

Vol. 113 18 2356-2367

Subject Categories

Meteorology and Atmospheric Sciences

Astronomy, Astrophysics and Cosmology

Atom and Molecular Physics and Optics


Basic sciences



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