Innovative Instrumentation for the Study of Atmospheric Aerosol Optical Properties

Aerosol optical properties (i.e. scattering and absorption) are of great im-portance to assess aerosol effects e.g. on visibility and Earth radiation bal-ance. In this paper, we present innovative optical instrumentation developed at the Department of Physics of the University of Milan: a multi-wavelength polar photometer (PP_UniMI) and a Single Particle Extinction and Scatter-ing (SPES). PP_UniMI is a filter-based device providing the aerosol absorp-tion coefficient of aerosol at 4 wavelengths (). Such measurements are of interest to have insights into the -dependent behavior of aerosol absorption properties, which is still poorly understood especially for what concerns weakly absorbing aerosol components. SPES allows to determine the size and refractive index of single particles. In case of absorbing particles, also in-formation on the imaginary part of the refractive index – very important es-pecially in the field of global models – can be provided with little assump-tions. We describe the main features of the two instruments and their ad-vantages and limitations. Examples of application are also presented.