Ground based in situ observations of filter_3pack at Ulborg (DK0031R). These measurements are gathered as a part of the following projects EMEP and they are stored in the EBAS database (http://ebas.nilu.no/). Parameters measured are: ammonium in aerosol (mass_concentration_of_ammonium_expressed_as_nitrogen_in_dry_aerosol_particles_in _air), chloride in aerosol (mass_concentration_of_chloride_in_dry_aerosol_particles_in _air), potassium in aerosol (mass_concentration_of_potassium_in_dry_aerosol_particles_in _air), sodium in aerosol (mass_concentration_of_sodium_in_dry_aerosol_particles_in _air), sulphate_corrected in aerosol (mass_concentration_of_sulphate_corrected_for_seaspray_expressed_as_sulphur_in_dry_aerosol_particles_in_air), sulphate_total in aerosol (mass_concentration_of_total_sulphateexpressed_as_sulphur_in_dry_aerosol_particles_in_air), sulphur_dioxide in air (mass_concentration_of_sulphur_dioxide_expressed_as_sulphur_in_air), sum_ammonia_and_ammonium in air+aerosol (mass_concentration_of_sum_ammonia_and_ammonium_in_aerosol), sum_nitric_acid_and_nitrate in air+aerosol (mass_concentration_of_sum_nitric_acid_and_nitrate_expressed_as_nitrogen_in_aerosol)