Spherical harmonic analysis of declination and secular geomagnetic variation 1550–1960

Ádám, Norbert; Baranova, T. N.; Ben'kova, N. P.; Cherevko, T. N.

doi:10.1016/0012-821x(70)90025-7

Cited by 12 publications

(7 citation statements)

References 1 publication

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“…4. The figure shows the rapid westerwardly drift of the plane of the quadrupole amounting to between 80 and 100 degrees longitude over the 360 year interval (YUKUTAKE and TACHINAKA , 1969;JAMES, 1970;ADAM et al, 1970;ROEDERER, 1974). As noted by JAMES (1970), the drift is not purely zonal; there is also an irregular meridional component.…”

mentioning

confidence: 80%

Auroral Zones in a Quadrupole Magnetosphere

Siscoe¹,

Crooker²

1976

J. geomagn. geoelec

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The nondipolar component of the geomagnetic field is likely to dominate during at least some geomagnetic reversals. The magnetosphere and auroral zones for a nondipolar field are more complex than for a dipole field. To begin to explore the nature of this complexity, we have studied the auroral zones appropriate to a pure quadrupole field. The quadrupole coefficients for the historical geomagnetic field were used in the study. The result is that such auroral zones are much more extensive than at present. They extend in association with two great circles from the tropics to midlatitudes in both north and south hemispheres. As a consequence, bombardment of the upper atmosphere by magnetosheath (polar cusp) and quasitrapped energetic magnetospheric (plasma sheet) particle is also much more extensive.

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confidence: 80%

Auroral Zones in a Quadrupole Magnetosphere

Siscoe¹,

Crooker²

1976

J. geomagn. geoelec

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“…Thus in addition to providing up-to-date dipole parameters I have also endeavored to put the parameters into an historical perspective by briefly indicating some of the changes that have taken place in the parameters over the last few centuries. Much has been written on these changes [e.g., Adam et al, 1970;Barraclough, 1974;Dawson and Newitt, 1982] and on the changes that have taken place over larger time scales [e.g., McElhinny and Senanayake, 1982]; my purpose is to indicate the direction of the changes that are likely over the next few decades.…”

Section: Introductionmentioning

confidence: 99%

Centered and eccentric geomagnetic dipoles and their poles, 1600–1985

Fraser–Smith¹

1987

Reviews of Geophysics

160

100

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“…In practice very few determinations of palaeomagnetic intensity have been made so that one must make use only of directional information. Adam et al (1970) first showed that the palaeointensity problem could be by-passed by noting that X i sin D i = Yi cos Di They combined (4) and (6) to obtain algebraic expressions which do not contain Fi but which can be solved for the G,. They referred to the solutions as X -X Y-2, Z-X and 2-H depending on which equation in (6) where U* is the transpose of U and (U*U)-' is the reciprocal of matrix (U*U).…”

Section: Spherical Harmonic Analysis Of Palaeomagnetic Datamentioning

confidence: 99%

“…The first study to make full use of both inclination and declination data was that of Creer, Georgi & Lowrie (1973). Their technique, an extension of work originally done by Adam et al (1970), combined values of the inclination and declination to yield a spherical harmonic analysis (see below). Since only directions but not intensity were used in the calculation, the resulting spherical harmonic coefficients were all relative to gIo.…”

Section: Introductionmentioning

confidence: 99%

A Method for Determining a Generalized Representation of Geomagnetic Field Sources

Verosub

1975

Geophysical Journal International

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A new method for modelling a geomagnetic field has been developed. After the directional data has been analysed in terms of spherical harmonics, a representation of the field sources is obtained as a combination of a geocentric axial dipole and an eccentric (not necessarily axial) dipole. The free parameters are the location of the eccentric dipole and the relative proportions of the field arising from the geocentric axial dipole and from the eccentric dipole.Previous models for field source configurations are included as special cases. The new method has the particular advantage that it emphasizes the choice among models rather than the fit to a pre-selected model.Analyses of synthetic data sets demonstrate the stability and accuracy of the method. A regionally-averaged set of late Cenozoic palaeomagnetic data can be best represented by a combination of 75-80 per cent geocentric dipole and 25-20 per cent eccentric dipole. The eccentric component of this configuration is displaced toward the North Pacific.

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Spherical harmonic analysis of declination and secular geomagnetic variation 1550–1960

Cited by 12 publications

References 1 publication

Auroral Zones in a Quadrupole Magnetosphere

Auroral Zones in a Quadrupole Magnetosphere

Centered and eccentric geomagnetic dipoles and their poles, 1600–1985

A Method for Determining a Generalized Representation of Geomagnetic Field Sources

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