Ground based in situ observations of aerosol_absorption_coefficient at Montseny (ES1778R) using filter_absorption_photometer. These measurements are gathered as a part of the following projects NOAA-ESRL, ACTRIS, GAW-WDCA and they are stored in the EBAS database (http://ebas.nilu.no/). Parameters measured are: aerosol_absorption_coefficient in pm10