Peculiarities of the geomagnetic field secular variations at the 20th solar activity cycle

Abstract

The decrease of solar and; correspondingly; geomagnetic activities at the 20th cycle has reflected on the secular variations of the geomagnetic field. On the continental magnetic observatories of the Earth north hemisphere (Europe and North America) the effect was positive and maximal amplitude was observed at the region of geomagnetic and magnetic poles. If the latitudes of the observatories diminishes amplitude of the effect also decreased and was about zero at the latitudes less 45°. At the Asia; the effect was negative and its maximal amplitude was observed at the observatory IRT. The sign of the effect changes at longitudes 60° (observatory KZN) and 150°—180° (observatory CWE; BRW). At the african and south America observatories the effect was not observed. The most probably; it was result of total variations from external and internal sources and the nearness of observatories to the geomagnetic equator. At Earth’s south hemisphere; the most of the observatories are costal or are placed on the is-lands. The effect was not observed at these observatories. Maybe the induction current of ocean flows compensates the external variations. At the Antarctic continent the little amplitude effect was observed at the south magnetic pole region (DRV).