More and more high quality data of aerosol optical properties, aerosol humidification, size distributions, black carbon and aerosol extinction vertical profiles have become available through international cooperation such as ACTRIS, GAW and NOAA networks. At the same time exhaustive global aerosol model results from renowned groups have been assembled in the AeroCom database. This session shall focus on model evaluation using the aerosol observations. Emphasis will be put to presentations which explore how the data may constrain aerosol concentrations, aerosol loads and radiative forcing.