Monday, 3 June 2002
Modeling optical properties of nonspherical mineral dust particles for remote sensing at solar wavelengths
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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