Surface-roughness effects on single-scattering properties of wavelength-scale particles

The effect of surface roughness in various size scales on the single-scattering properties of wavelength-scale particles is studied. The model simulations are carried out using the discrete-dipole approximation and the model particle shapes are generated using a harmonic Gaussian-random-sphere geometry. The model simulations are ensemble-averaged over a small sample of 10 model particles for each parameter combination to eliminate interference effects associated with specific model shapes. The results indicate that the effect of surface roughness on scattering cannot be considered independently of the host particle. Rather, the effectiveness of surface roughness to affect scattering depends on the particle size. The general trend for the wavelength-scale particles appears to be that a surface roughness in a given size-scale affects scattering more on large than on small particles. It is also found that a decrease in the size-scale of surface roughness clearly tends to decrease the single-scattering albedo.