Modelling light scattering by mineral dust using spheroids: Assessment of applicability
- ISSN: 16807316
- DOI: 10.5194/acp-11-5347-2011
We study the applicability of spheroidal model particles for simulating the single-scattering optical properties of mineral dust aerosols. To assess the range of validity of this model, calcula-tions are compared to laboratory observations for five different dust samples at two wavelengths. We further investigate whether the best-fit shape distributions of spheroids for different mineral dust samples have any similarities that would allow us to suggest a generic first-guess shape distribu-5 tion for suspended mineral dust. We find that best-fit shape distributions vary considerably between samples and even between wavelengths, making definitive suggestions for a shape distribution dif-ficult. The best-fit shape distribution also depends strongly on the refractive index assumed and the cost function adopted. However, a power-law shape distribution which favours those spheroids that depart most from the spherical shape is found to work well in most cases. To reproduce ob-10 served asymmetry parameters, best results are obtained with a power-law shape distribution with an exponent around three.