In search of long-term hemispheric asymmetry in the geomagnetic field: Results from high northern latitudes

Abstract

Investigations of the behavior of the geomagnetic field on geological timescales rely on globally distributed data sets from dated lava flows. We present the first suitable data from the Arctic region, comprising 37 paleomagnetic directions from Jan Mayen (71°N, 0.2-461 ka) and Spitsbergen (79°N, 1-9.2 Ma) and five paleointensity results. Dispersion of the Arctic virtual geomagnetic poles over the last 2 Ma (27.3 ± 4.0°) is significantly lower than that from published Antarctic data sets (32.1 ± 5.0°). Arctic average virtual axial dipole moment (76.8 ± 24.3 ZAm2) is high in comparison to Antarctica over the same time interval (34.8 ± 8.2 ZAm2), although the data are still too sparse in the Arctic to be definitive. These data support a long-lived hemispheric asymmetry of the magnetic field, contrasting higher, more stable fields in the north with lower average strength and more variable field directions in the south. Such features require significant non-axial-dipole contributions over 105-106 years. © 2013. American Geophysical Union. All Rights Reserved