Eccentric geomagnetic dipole drift

Cain, J. C.; Schmitz, Dave R.; Kluth, Christopher

doi:10.1016/0031-9201(85)90136-0

Cited by 15 publications

(2 citation statements)

References 17 publications

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“…The studies of the westward drift of the eccentric dipole of Earth and the length of day (1.o.d.) fluctuations by Vestine and Kahle [1967] and recently by Cain et al [1985] are searches for the physical evidence of this close relation. Another type of search involves the power spectral density analyses of the geomagnetic field and the 1.o.d.…”

Section: Introduction Data and Methods Of Analysismentioning

confidence: 61%

Cross correlation of the variations of the geomagnetic dipole moment and the fluctuations of Earth's rotation

Jin¹

1992

J. Geophys. Res.

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The origin of the main geomagnetic field is related to the current in the fluid core of Earth. A close relationship between the fluctuations of the rotation of Earth and the secular changes of the geomagnetic field is suspected. Two‐channel maximum entropy spectral analyses are applied to the dipole moments of Earth from 1901 to 1980 and the rotational rate fluctuations from 1890 to 1987 in this study. The common spectral peaks are found with periods of 51, 34, 22, 13, and 9.5 years. The values of the coherence are above 0.99, 0.98, 0.95, 0.95, and 0.77 at these peaks. The 51‐ and 34‐year spectral peaks are the dominant ones. The time lags of the magnetic field are 3.1 ± 0.6 years and 22.4 ± 4.5 years, respectively. Two simulated time series are constructed with the obtained time lags. They exhibit features similar to the actual time series of the dipole moment variations and Earth's rotational fluctuations.

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Section: Introduction Data and Methods Of Analysismentioning

confidence: 61%

Cross correlation of the variations of the geomagnetic dipole moment and the fluctuations of Earth's rotation

Jin¹

1992

J. Geophys. Res.

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“…There have been many studies about the relation between the decadal magnetic field variation and 1.o.d. fluctuations (Vestine & Kahle 1968;Hide 1969;Yukutake 1973;Braginsky 1984;Courtillot & Le Mouel 1984;Stix & Roberts 1984;Cain, Schmitz & Kluth 1985;Gire & Le Mouel 1986;Langel et al 1986;Jault et af. 1988;Jault & Le Mouel 1989;Yokoyama & Yukutake 1991, 1992) Although there appears to be a clear correlation between the two phenomena, the physical mechanism is controversial.…”

Section: Introductionmentioning

confidence: 99%

The westward drift of the geomagnetic field caused by length-of-day variation, and the topography of the core-mantle boundary

Yoshida

Hamano

1993

Geophysical Journal International

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S U M M A R YWe propose that the westward drift of the geomagnetic field is caused by length-of-day (1.o.d.) variation through topographic coupling between the mantle and the core. Fluctuations of the rotation velocity of the mantle induce radial flow in the core through topographic coupling at the core-mantle boundary (CMB). The induced flow bends the toroidal field to generate a poloidal field which appears to drift westwards. A n analytical model is constructed to describe this situation on the basis of a quasi-geostrophic approximation. We compare our model with observations of the geomagnetic field over the last several hundred years. When the sectorial harmonic components of the Gauss coefficients, g z and h x , are plotted on a diagram with g as the abscissa and h as the ordinate, the observed trajectories follow a clockwise ellipse. The clockwise motion on the g-h plot signifies that the pattern of the magnetic field moves westwards. This behaviour is described well by our model if 1.o.d. variation is assumed to consist of one Fourier component. We find that the period of the Fourier component of 1.o.d. variation is about 700 yr. The relationship between the ellipticity of the trajectories and the eigenfrequencies of the slow magnetohydrodynamic oscillations enables us to infer the dispersion relation to the oscillations, which signifies that the strength of the toroidal field of the outer core is 50-100Gauss. We derive the topography of the CMB from the directions of the axes of the ellipses. The CMB topography is found to correlate well with the lower mantle structure.

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2009

The Interaction Between Earth's Rotation and Geophysical Processes

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Eccentric geomagnetic dipole drift

Cited by 15 publications

References 17 publications

Cross correlation of the variations of the geomagnetic dipole moment and the fluctuations of Earth's rotation

Cross correlation of the variations of the geomagnetic dipole moment and the fluctuations of Earth's rotation

The westward drift of the geomagnetic field caused by length-of-day variation, and the topography of the core-mantle boundary

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