Ground based in situ observations of aerosol_optical_depth at Ny-Ålesund (NO0057R) using sun_tracking_filter_radiometer. These measurements are gathered as a part of the following projects GAW-WDCA, NILU and they are stored in the EBAS database (http://ebas.nilu.no/). Parameters measured are: aerosol_optical_depth in aerosol (atmosphere_optical_thickness_due_to_ambient_aerosol_particles), aerosol_optical_depth in aerosol (atmosphere_optical_thickness_due_to_ambient_aerosol_particles), aerosol_optical_depth in aerosol (atmosphere_optical_thickness_due_to_ambient_aerosol_particles)