Reversals and large-scale variations of the geomagnetic field: similarities and differences
Affiliation:
1. Schmidt Institute of Physics of the Earth
Abstract
It is shown that during reversals in geodynamo models the minimum amplitudes of the
dipole, quadrupole and octupole coincide. Since the characteristic time of the reversal is
close to the oscillations of the large-scale geomagnetic field, a similar analysis was carried
out for the minima of the amplitude of the dipole magnetic field over the past 100 thousand
years. It turned out that in this case such synchronization also occurs. It can be assumed
that reversals and large scale variations of the geomagnetic field between the reversals have
a lot in common. The wavelet analysis carried out indicates that the concept of the main
geodynamo cycle is very arbitrary: the period of oscillation can vary from 8-10 thousand
years to 20-30 thousand for a dipole. Analysis of the evolution of the Mauersberger spectrum
allows us to conclude that magnetic field fluctuations observed at the Earth’s surface are
associated with the transfer of the magnetic field to the surface of the liquid core and can
hardly be described by functions periodic in time.
Publisher
Geophysical Center of the Russian Academy of Sciences
Reference13 articles.
1. Bonhommet, N., and J. Zähringer (1969), Paleomagnetism and potassium argon age determinations of the Laschamp geomagnetic polarity event, Earth and Planetary Science Letters, 6(1), 43–46, https://doi.org/10.1016/0012-821X(69)90159-9., Bonhommet, N., and J. Zähringer (1969), Paleomagnetism and potassium argon age determinations of the Laschamp geomagnetic polarity event, Earth and Planetary Science Letters, 6(1), 43–46, https://doi.org/10.1016/0012-821X(69)90159-9. 2. Christensen, U., P. Olson, and G. A. Glatzmaier (1999), Numerical modelling of the geodynamo: a systematic parameter study, Geophysical Journal International, 138(2), 393–409, https://doi.org/10.1046/j.1365-246x.1999.00886.x., Christensen, U., P. Olson, and G. A. Glatzmaier (1999), Numerical modelling of the geodynamo: a systematic parameter study, Geophysical Journal International, 138(2), 393–409, https://doi.org/10.1046/j.1365-246x.1999.00886.x. 3. Christensen, U. R., and J. Aubert (2006), Scaling properties of convection-driven dynamos in rotating spherical shells and application to planetary magnetic fields, Geophysical Journal International, 166(1), 97–114, https://doi.org/10.1111/j.1365-246x.2006.03009.x., Christensen, U. R., and J. Aubert (2006), Scaling properties of convection-driven dynamos in rotating spherical shells and application to planetary magnetic fields, Geophysical Journal International, 166(1), 97–114, https://doi.org/10.1111/j.1365-246x.2006.03009.x. 4. Hulot, G., and J. L. Le Mouël (1994), A statistical approach to the Earth’s main magnetic field, Physics of the Earth and Planetary Interiors, 82(3–4), 167–183, https://doi.org/10.1016/0031-9201(94)90070-1., Hulot, G., and J. L. Le Mouël (1994), A statistical approach to the Earth’s main magnetic field, Physics of the Earth and Planetary Interiors, 82(3–4), 167–183, https://doi.org/10.1016/0031-9201(94)90070-1. 5. Krause, F., and K.-H. Rädler (1980), Mean-field magnetohydrodynamics anddynamo theory, Akademie-Verlag, Berlin., Krause, F., and K.-H. Rädler (1980), Mean-field magnetohydrodynamics anddynamo theory, Akademie-Verlag, Berlin.
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