11th Conference on Atmospheric Radiation and the 11th Conference on Cloud Physics

Monday, 3 June 2002
Modeling optical properties of nonspherical mineral dust particles for remote sensing at solar wavelengths
Olga V. Kalashnikova, Univ. of Colorado, Boulder, CO; and I. N. Sokolik
The empirical data have shown that mineral dust particles have complex morphology and composition, and wavelength-dependent refractive indices. In addition, the optical properties of mineral dust mixtures may vary significantly over different geographical regions. We will be presenting a new approach establishing a physically based relationship between source-dependent morphology/composition of dust particles and their optics. Our approach links morphology and mineralogy data provided by the individual-particle analysis (IPA) and computations of the dust optical properties with a Discrete Dipole Approximation. The approach was applied to a statistically representative number of dust particles collected in the atmosphere over China and Japan. We demonstrate that the presence of angular-type particles of different thicknesses and circularities reported by IPA data causes various differences in the scattering phase functions and single scattering albedo compared to those of volume-equivalent spheres or ellipses. These differences are sufficiently large as to affect the retrievals of aerosol optical properties from satellite and ground-based remote sensing observations at the solar wavelengths.

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