Tracking geomagnetic impulses at the core-mantle boundary
Emmanuel Dormya,b
Mioara Mandeaa,c
aInstitut de Physique du Globe de Paris, 4 place Jussieu, F-75252, Paris, France.
bC.N.R.S / L.P.S., Ecole Normale Supérieure, 24 rue Lhomond,
75231 Paris Cedex 05, France.
cGeoForschungsZentrum Potsdam, Telegrafenberg, 14473 Potsdam,
Germany.
Earth and Planetary Science Letters 237 (2005) 300-309
Abstract.
The main magnetic field of the Earth is generated and maintained by
convective motions in the fluid outer core. Temporal
field variations occur on an impressive variety of scales, ranging from
months to millions of years. Among these, the most
intriguing features are geomagnetic bimpulsesQ or bjerksQ [V. Courtillot,
J. Ducruix and J.L. Le Moue(l, Sur une acce4le4ration
re4cente de la variation se4culaire du champ magne4tique terrestre,
Acad. Sci. Paris C.R., D287, (1978) 10951098., J.L. Le
Moue(l, J. Ducruix and C. Ha Duyen, Geophys. Res. Lett., 5, (1983)
369. [1,2]]. Here, we investigate these very rapid events at
the surface of the Earths core using a global model, designed for use at
this depth. We identify two regions of very active
variations, where wave-like structures propagate. The geometrical
characteristics of these wave-like motions provide new
constraints on the intricate dynamics of the core.
Supplementary information can be downloaded here.