Ground based in situ observations of filter_3pack at Ulborg (DK0031R). These measurements are gathered as a part of the following projects CAMP, EMEP 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), sum_ammonia_and_ammonium in air+aerosol (mass_concentration_of_sum_ammonia_and_ammonium_in_aerosol)