Effect of Aerosols on Atmospheric Environment

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1. Optical properties of aerosolsTheoretical calculation was made for refractive indices of aerosol particles of both internally and externally mixed with different substances, and results gave higher absorption for internally mixed particles, in particular, in the size range larger than 0.2um. Telescope method which has been developed by the group of University of Vienna was applied to determine the refractive index of atmospheric aerosols in Uji area, and local characteristics were examined by comparing with the data obtained in Vienna.2. Characterization of atmospheric aerosolsChemical elements of atmospheric aerosols sampled at both Uji and Vienna were analyzed with PIXE method, and it was found that fine aerosols in Vienna contains more sulfur and lead than in those in Uji. Chemical components of Kosa aerosols originated from Asian continent were also analyzed and the optical properties of those particles are under the examination.3. Evaluation of effects of aerosols on atmospheric environmentA computational model, LOWTRAN, developed by AFGL was employed to calculate the solar energy intensity at the earth surface for different conditions of aerosols. Aerosol models to be used in the model are being examined based on more realistic properties of aerosols, i.e., the size distribution, vertical profile of concentration and the refractive index. Viennese group presented a simple model for evaluating the effects of aerosols on the solar radiative force by taking into consideration of both direct and indirect effects of aerosols. Calculated results show that the order of magnitude of aerosols on the radiative force is about -0.5 or -1.0 W/m^2 with the increase of aerosols after the pre-industrialized period, and this is the order of compensating the global warming by CO_2. Usefulness of this model will need further study based on more reliable field data.