Mundt, W.W.Mundt2022-03-022022-03-021986https://publica.fraunhofer.de/handle/publica/174260For 11 European magnetic observatories, the periodic parts in the annual means have been calculated and discussed. The amplitudes of these solar-cycle effects are about 2' for D and 10 nT for H and Z for mid-latitude stations, but about 3' for D and 15-18 nT for H and Z for observatories in the auroral zone. These effects have to be taken into account by analysing the regional fine-structure of the secular variation.engeomagnetic variationssolar activitysolar-terrestrial relationshipssolar terrestrial relationsunannual meanseuropean geomagnetic observatoriesamplitudessolar-cycle effectsmid-latitude stationsauroral zoneregional fine-structuresecular variation621journal article