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.
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Alexandrescu, M., D. Gibert, G. Hulot, J.-L. Le Mouël, and G. Saracco, Worldwide analysis of geomagnetic jerks, J. Geophys. Res., 101, 21975–21994, 1996.
Barton, C., Survey Tracks Current Position of South Magnetic pole, EOS, 83(27), 291, 2002.
Carlut, J., V. Courtillot, and G. Hulot, Over how much time should the geomagnetic field be averaged to obtain the mean paleomagnetic field? Terra Nova, 11(5), 239–243, 2000.
Courtillot, V., J. Ducruix, and J.-L. Le Mouël, Sur une accélération récente de la variation séculaire du champ magnétique terrestre, C. R. Acad. Sci. D, 287, 1095–1098, 1978.
Fraser-Smith, A. C., Centered and eccentric geomagnetic dipoles and their poles, 1600–1985, Rev. Geophys., 25, 1–16, 1987.
Hope, E. R., Linear secular oscillation of the northern magnetic pole, J. Geophys. Res., 62-1, 19–27, 1957.
Hulot, G., C. Eymin, B. Langlais, M. Mandea, and N. Olsen, Small-scale structure of the geodynamo inferred from Oersted and Magsat satellite data, Nature, 416, 620–623, 2002.
Jackson, A., A. Jonkers, and M. Walker, Four centuries of geomagnetic secular variation from historical records, Phil. Trans. R. Soc. Lond., 358, 957–990, 2000.
Langlais, B., M. Mandea, and P. Ultré-Guérard, High-resolution magnetic field modeling: application to MAGSAT and Ørsted data, Phys. Earth Planet. Int., 2003 (in press).
Le Huy, M., M. Alexandrescu, G. Hulot, and J.-L. Le Mouël, On the characteristics of successive geomagnetic jerks, Earth Planets Space, 50, 723–732, 1998.
Malin, S. R. C., B. H. Hodder, and D. R. Barraclough, Geomagnetic secular variation: A jerk in 1970, in 75th Anniversary Volume of Ebro Observatory, edited by J. O. Cardus, pp. 239–256, Roquetes, Tarragona, Spain, 1983.
Mandea, M. and S. Macmillan, International Geomagnetic Reference Field—The Eighth Generation, Earth Planets Space, 52, 1119–1124, 2000.
Nagao, H., T. Iyemori, T. Higuchi, S. Nakano, and T. Araki, Local time features of geomagnetic jerks, Earth Planets Space, 54, 119–131, 2002.
Newitt, L. R., M. Mandea, L. A. McKee, and J.-J. Orgeval, Recent acceleration of the North Magnetic Pole linked to magnetic jerks, EOS, 83, 381–388, 2002.
Olsen, N., R. Holme, G. Hulot, T. Sabaka, T. Neubert, L. Toeffner-Clausen, F. Primdahl, J. Joergensen, J.-M. Leger, D. Barraclough, J. Bloxham, J. Cain, C. Constable, V. Golovkov, A. Jackson, P. Kotze, B. Langlais, S. Macmillan, M. Mandea, J. Merayo, L. Newitt, M. Purucker, T. Risbo, M. Stampe, A. Thomson, and C. Voorhies, Oersted Initial Field Model (OIFM), Geophys. Res. Lett., 27(22), 3607–3610, 2000.
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Mandea, M., Dormy, E. Asymmetric behavior of magnetic dip poles. Earth Planet Sp 55, 153–157 (2003). https://doi.org/10.1186/BF03351742
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DOI: https://doi.org/10.1186/BF03351742