Magnetic poles and dipole tilt variation over the past decades to millennia

Abstract

Due to the strong dipolar character of the geomagnetic field the shielding effect against cosmic and solar ray particles is weakest in the polar regions. We here present a comprehensive study of the evolution of magnetic and geomagnetic pole locations and the Earth's magnetic core field in both polar regions over the past few years to millennia. North and south magnetic poles change independently according to the asymmetric complexity of the field in the two hemispheres, and the changes are not correlated to variations of the dipole axis. The recent, strong acceleration of the north magnetic pole motion appears to be linked to a reverse flux patch at the coremantle boundary, and an increasing deceleration of the pole over the next years seems likely. Over the whole studied period of 7000 years two periods of comparatively high velocity of the north magnetic pole are observed at 4500 BC and 1300 BC, based on the presently available data and models. Geographic latitudes and longitudes of magnetic and geomagnetic poles based on the studied geomagnetic field models are available together with animations of the poles and polar field behaviour from our webpage http:// www.gfz-potsdam.de/geomagneticfield/poles. Copyright © The Society of Geomagnetism and Earth, Planetary and Space Sciences (SGEPSS); The Seismological Society of Japan; The Volcanological Society of Japan; The Geodetic Society of Japan; The Japanese Society for Planetary Sciences; TERRAPUB.