Ground based in situ observations of sulphate_corrected at Birkenes (NO0001R) using filter_3pack. These measurements are gathered as a part of the following projects CAMP, EMEP, NILU and they are stored in the EBAS database (http://ebas.nilu.no/). Parameters measured are: sulphate_corrected in aerosol (mass_concentration_of_sulphate_corrected_for_seaspray_expressed_as_sulphur_in_dry_aerosol_particles_in_air)