Perturbations of the Earths rotation and their implications for the present-day mass balance of both polar ice caps

Mean hourly values of the horizontal and vertical components of the geomagnetic field at six observatories on the Iberian Peninsula were analysed to study seasonal and spatial behaviour of the solar and lunar (ionospheric and oceanic) daily geomagnetic variations. The results are tabulated and their characteristics are discussed. The influence of local oceanic effects on the lunar oceanic contribution at the peninsular observatories is noted. In particular, the spatial behaviour of the lunar oceanic contribution is considered. Whereas the mean value for the Peninsula is consistent with that expected according to an existing model for electric currents in the eastern Atlantic Ocean, individual values are not. The influence of tide in the Mediterranean Sea, of water currents in the Strait of Gibraltar and of local effects in the Atlantic Ocean is proposed as the reason for this behaviour.