Asymmetric behavior of magnetic dip poles
Mioara Mandea, and Emmanuel Dormy,
Institut de Physique du Globe de Paris,
4, place Jussieu, 75252 Paris cedex 05, France.
Earth Planets Space, 55, 3,
pages 153-157, April 2003.
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.