Results 81 to 90 of about 1,181 (116)

Geomagnetic Core Field Secular Variation Models

Space Science Reviews, 2009
We analyse models describing time changes of the Earth’s core magnetic field (secular variation) covering the historical period (several centuries) and the more recent satellite era (previous decade), and we illustrate how both the information contained in the data and the a priori information (regularisation) affect the result of the ill-posed ...
Gillet, N., Lesur, V., Olsen, N.
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Modelling the geomagnetic field

Geophysical Journal International, 1983
Summary. The progress of geomagnetic field modelling is traced from 1600 to the present day, with particular emphasis on the method of spherical harmonic analysis, illustrated by examples taken mainly from British sources. No attempt is made to be comprehensive (a catalogue of models has been given elsewhere by Barraclough) or to include models of ...
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Uncertainty estimates in geomagnetic field modeling

Journal of Geophysical Research: Solid Earth, 1989
Geomagnetic field models usually consist of coefficients of a truncated spherical harmonic analysis derived by a weighted least squares analysis. The data are typically assumed to be uncorrelated, and an estimated, diagonal, data covariance matrix is incorporated as an inverse weighting function. Accuracy estimates on the derived coefficients are taken
R. A. Langel, R. H. Estes, T. J. Sabaka
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Dynamic geomagnetic field models

Geomagnetism and Aeronomy, 2011
A review of modern dynamic models of the Earth’s magnetosphere (the A2000 paraboloid model and Tsyganenko’s T01 model) is presented. For the magnetic storm of January 9–11, 1997, the results of joint calculations of the magnetospheric magnetic field are presented and contributions of the large-scale magnetospheric currents to the Dst variations are ...
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Geomagnetic Core Field Models in the Satellite Era

2010
After a brief review of the theoretical basis and difficulties that modelers are facing, we present three recent models of the geomagnetic field originating in the Earth’s core. All three modeling approaches are using recent observatory and near-Earth orbiting survey satellite data. In each case the specific aims and techniques used by the modelers are
Lesur, V., Olsen, N., Thomson, A.
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Poloidal and toroidal fields in geomagnetic field modeling

Reviews of Geophysics, 1986
The theory of surface operators is described and applied to four surface operators on spheres: the dimensionless surface gradient, ▽1=r▽‐r∂r; the dimensionless surface curl, ; the dimensionless surface Laplacian, ▽1²=▽1 · ▽1; and the Funk‐Hecke operators, integral operators with axisymmetric kernels.
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Mathematical model of the geomagnetic field for 1965

Journal of Geophysical Research, 1966
A mathematical model of the geomagnetic field for 1965.0 is presented. The field is given by internal and external spherical harmonic coefficients to degree and order 12. This model was derived from approximately 425,000 measurements made since 1900. An important step in the derivation was the analytic smoothing of data, which produced the regularly ...
L. Hurwitz, D. G. Knapp, J. H. Nelson, D. E. Watson   +3 more
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A Phenomenological Model for Reversals of the Geomagnetic Field

1989
We consider a system made by N point interacting dipoles, each of them having a finite lifetime. A renewal process for the dipoles gives the time evolution of the system. When the number N of dipoles is low, and for a wide range of the coupling between the dipoles, we observe sudden transitions or excursions between two polarised states.
Mazaud, A., Laj, C., Bard, E.
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An Overview of Geomagnetic Field Models

1980
Abstract : Over the last decade, the utility of geomagnetic field models or the mathematical representations of the geomagnetic field has expanded considerably, both for civilian and military applications. Such an increase has been accompanied with more interest in models and demands for better accuracies with resultant changes in techniques of model ...
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Mathematical Methods of Geomagnetic Field Modeling

2017
The geomagnetic field, as the Earth’s magnetic field is called, extends from Earth’s interior to outer space. The magnetosphere is the region defined by the areal extent and the shape of the magnetic field of a celestial body, like the planet Earth.
Stavros Kolios, Andrei V. Vorobev, Gulnara R. Vorobeva, Chrysostomos Stylios   +3 more
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