Possibilities to retrieve aerosol size distribution and exact value of the scattering coefficient using the measurement data of the polar nephelometer Aurora 4000 are analyzed. It is shown that only the fine aerosol fraction can be reliable recovered. The examples of the results of the inverse problem solution are presented. Two approaches to the clarification of the value of scattering coefficient value – multiple regression and recalculation through inversion procedure (microphysical extrapolation) – are considered.