The Arctic region represents a sensitive ecosystem, which is susceptible to even small changes in the local climate. Special conditions of usually high surface albedo and low solar elevations cause enhanced aerosol/cloud effects due to multiple scattering. It is suspected that this increased interaction between solar radiation and the aerosol particles/clouds magnifies their radiative impact. Thus, for a given aerosol distribution, the specific optical properties are enhanced in the polar regions. For the same reasons, results from field experiments at low latitudes are difficult to transfer to polar regions and as a consequence there is an urgent need to conduct specific measurement programs in high latitude regions. In order to improve the knowledge about the origin, transport pathways, vertical structure of aerosol physical and chemical properties as well as the impact on climate in the polar regions, a combined effort of surface-based, airborne and spaceborne measurements is needed. Therefore, this proposed project is aiming at a determination of the vertical structure of the chemical, physical and optical properties of Arctic aerosol particles, including solar radiative closure between observed and calculated aerosol properties (direct climate effect)