Solar-cycle effects in annual means of European geomagnetic observatories
Abstract
For 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.
