D. W. Allan and E. C. Bullard, The secular variation of the earth's magnetic field, Proc. Cambridge Philos. Soc, pp.783-809, 1966.
DOI : 10.1098/rsta.1954.0018

H. Amit, P. Olson, and U. R. Christensen, Tests of core flow imaging methods with numerical dynamos, Geophysical Journal International, vol.168, issue.1, pp.27-39, 2007.
DOI : 10.1111/j.1365-246X.2006.03175.x

J. Aubert, J. Aurnou, and J. Wicht, The magnetic structure of convection?driven numerical dynamos, Geophys, J. Int, vol.172, pp.945-956, 2008.

G. E. Backus, Kinematics of Geomagnetic Secular Variation in a Perfectly Conducting Core, Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences, vol.263, issue.1141, pp.239-266, 1968.
DOI : 10.1098/rsta.1968.0014

J. Bloxham, The expulsion of magnetic flux from the Earth's core, Geophysical Journal International, vol.87, issue.2, pp.669-678, 1986.
DOI : 10.1111/j.1365-246X.1986.tb06643.x

A. Chulliat, Geomagnetic secular variation generated by a tangentially geostrophic flow under the frozen?flux assumption?Part II. Sufficient conditions, Geophys, J. Int, vol.157, pp.537-552, 2004.

A. Chulliat and G. Hulot, Local computation of the geostrophic pressure at the top of the core, Physics of the Earth and Planetary Interiors, vol.117, issue.1-4, pp.309-328, 2000.
DOI : 10.1016/S0031-9201(99)00104-1

A. Chulliat and N. Olsen, Observation of magnetic diffusion in the Earth's outer core from Magsat, ??rsted, and CHAMP data, Journal of Geophysical Research, vol.111, issue.B5, pp.10-1029, 2010.
DOI : 10.1029/2009JB006994

C. G. Constable, R. L. Parker, and P. Stark, Geomagnetic field models incorporating frozen-flux constraints, Geophysical Journal International, vol.113, issue.2, pp.419-433, 1993.
DOI : 10.1111/j.1365-246X.1993.tb00897.x

V. Courtillot, J. Ducruix, and J. ?. , Sur une accélération récente de la variation séculaire du champ magnétique terrestre, C. R. Acad. Sci. Ser. D, vol.287, pp.1095-1098, 1978.

D. Gubbins, Geomagnetic constraints on stratification at the top of the Earth's core, Earth Planets Space, pp.661-664, 2007.

D. Gubbins and N. Roberts, Use of the frozen flux approximation in the interpretation of archaeomagnetic and palaeomagnetic data, Geophysical Journal International, vol.73, issue.3, pp.675-687, 1983.
DOI : 10.1111/j.1365-246X.1983.tb03339.x

D. Gubbins and P. H. Roberts, Magnetohydrodynamics of the Earth's core, in Geomagnetism, pp.1-183, 1987.

R. Holme and N. Olsen, Core surface flow modelling from high? resolution secular variation, Geophys, J. Int, vol.166, pp.518-528, 2006.

G. Hulot and A. Chulliat, On the possibility of quantifying diffusion and horizontal Lorentz forces at the Earth???s core surface, Physics of the Earth and Planetary Interiors, vol.135, issue.1, pp.47-54, 2003.
DOI : 10.1016/S0031-9201(02)00191-7

G. Hulot, T. J. Sabaka, and N. Olsen, The present field, Geomagnetism , Treatise on Geophysics, pp.33-75, 2007.

A. Jackson, A. R. Jonkers, and M. Walker, Four centuries of geomagnetic secular variation from historical records, Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences, vol.358, issue.1768, pp.957-990, 2000.
DOI : 10.1098/rsta.2000.0569

A. Jackson, C. G. Constable, M. R. Walker, and R. L. Parker, Models of Earth's main magnetic field incorporating flux and radial vorticity constraints, Geophysical Journal International, vol.171, issue.1, pp.133-144, 2007.
DOI : 10.1111/j.1365-246X.2007.03526.x

L. Mouël and J. ?. , Outer core geostrophic flow and secular variation of Earth's geomagnetic field, Nature, pp.311-734, 1984.

S. Macmillan, A geomagnetic jerk for the early 1990's, Earth and Planetary Science Letters, vol.137, issue.1-4, pp.189-192, 1996.
DOI : 10.1016/0012-821X(95)00214-W

M. Mandea and E. Dormy, Asymmetric behavior of magnetic dip poles, Earth Planets Space, pp.153-157, 2003.

M. Mandea, E. Bellanger, and J. ?. , A geomagnetic jerk for the end of the 20th century?, Earth and Planetary Science Letters, vol.183, issue.3-4, pp.369-373, 2000.
DOI : 10.1016/S0012-821X(00)00284-3

L. R. Newitt and C. E. Barton, The Position of the North Magnetic Dip Pole in 1994., Journal of geomagnetism and geoelectricity, vol.48, issue.2, pp.221-232, 1996.
DOI : 10.5636/jgg.48.221

L. R. Newitt and A. Chulliat, Comment on ???Will the Magnetic North Pole Move to Siberia????, Eos, Transactions American Geophysical Union, vol.88, issue.51, p.571, 2007.
DOI : 10.1029/2007EO510005

L. R. Newitt, M. Mandea, L. A. Mckee, and J. J. Orgeval, Recent acceleration of the north magnetic pole linked to magnetic jerks, Eos, Transactions American Geophysical Union, vol.124, issue.35, p.381, 2002.
DOI : 10.1029/2002EO000276

L. R. Newitt, A. Chulliat, and J. J. Orgeval, Location of the North Magnetic Pole in April 2007, Earth, Planets and Space, vol.124, issue.6, pp.703-710, 2007.
DOI : 10.1186/BF03353178

N. Olsen and M. Mandea, Will the magnetic North Pole move to Siberia?, Eos, Transactions American Geophysical Union, vol.159, issue.35, p.293, 2007.
DOI : 10.1111/j.1365-246X.2004.02.421.x.

N. Olsen and M. Mandea, Investigation of a secular variation impulse using satellite data: The 2003 geomagnetic jerk, Earth and Planetary Science Letters, vol.255, issue.1-2, pp.94-105, 2007.
DOI : 10.1016/j.epsl.2006.12.008

N. Olsen, M. Mandea, T. J. Sabaka, and L. Tøffner?clausen, CHAOS-2?????????a geomagnetic field model derived from one decade of continuous satellite data, Geophysical Journal International, vol.179, issue.3, pp.1477-1487, 2009.
DOI : 10.1111/j.1365-246X.2009.04386.x

P. Olson and J. Aurnou, A polar vortex in the Earth's core, Nature, vol.402, issue.6758, pp.170-173, 1999.
DOI : 10.1038/46017

A. Pais and G. Hulot, Length of day decade variations, torsional oscillations and inner core superrotation: evidence from recovered core surface zonal flows, Physics of the Earth and Planetary Interiors, vol.118, issue.3-4, pp.291-316, 2000.
DOI : 10.1016/S0031-9201(99)00161-2

P. H. Roberts and S. Scott, On Analysis of the Secular Variation, Journal of geomagnetism and geoelectricity, vol.17, issue.2, pp.137-151, 1965.
DOI : 10.5636/jgg.17.137

J. C. Ross, On the position of the north magnetic pole, Philos. Trans. R. Soc. London, vol.124, pp.46-51, 1834.

T. J. Sabaka, N. Olsen, and M. Purucker, Extending comprehensive models of the Earth's magnetic field with ??rsted and CHAMP data, Geophysical Journal International, vol.159, issue.2, pp.521-547, 2004.
DOI : 10.1111/j.1365-246X.2004.02421.x

L. Shure, R. L. Parker, and G. Backus, Harmonic splines for geomagnetic modelling, Physics of the Earth and Planetary Interiors, vol.28, issue.3, pp.215-229, 1982.
DOI : 10.1016/0031-9201(82)90003-6

I. Wardinski and R. Holme, A time?dependent model of the Earth's magnetic field and its secular variation for the period, J. Geophys. Res, pp.10-1029, 1980.