Dust optical properties retrieved from ground-based polarimetric measurements

摘要

We have systematically processed one year of sunphotometer measurements (recorded at five AERONET/PHOTONS sites in Africa) in order to assess mineral dust optical properties with the use of a new polarimetry-based algorithm. We consider the Cimel CE318 polarized sunphotometer version to obtain single-scattering albedo, scattering phase matrix elements F_(11) and F_(12) for dust aerosols selected with Angstrom exponents ranging from -0.05 to 0.25. Retrieved F_(11) and F_(12) differ significantly from those of spherical particles. The degree of linear polarization -F_(12)/F_(11) for single scattering of atmospheric total column dust aerosols in the case of unpolarized incident light is systematically retrieved for the first time to our knowledge from sunphotometer measurements and shows consistency with previous laboratory characterizations of nonspherical particles.