Asymmetric behavior of magnetic dip poles

Abstract

The north magnetic dip pole velocity has more than doubled in the last 30 years. This observation, together with the decrease in the Earth's magnetic dipole intensity over the last century has raised the concern of a possible approaching polarity reversal. We show that this rapid variation is in fact to be expected, and will not affect the dipolar field as a whole, but only the north magnetic pole. We demonstrate how this rapid displacement of the north magnetic pole is made possible by the horizontal field morphology. This rapid variation of north magnetic pole position does not imply any important modification of the core processes associated with field generation. The north magnetic pole position being very sensitive to small as well as rapid variations of the field, we show that it can very effectively be used as a passive tracer (or indicator) of field variations. Indeed, its velocity over the last century very accurately indicates the geomagnetic impulses (or jerks) that were so far observed only in observatory data. 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.