Results 261 to 270 of about 21,118 (299)

A model of the geomagnetic field for 1970

Journal of Geophysical Research, 1974
A mathematical description of the geomagnetic field for 1970 has been derived by using 360,000 land, sea, and airborne measurements accumulated since 1939. The model is expressed by 168 spherical harmonic coefficients gnm, hnm to m = n = 12. It was used as the basis for the 1970 edition of the U.S. World Charts of Magnetic Variation.
Louis Hurwitz, Eugene B. Fabiano, Norman W. Peddie   +2 more
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A model of the geomagnetic field for 1975

Journal of Geophysical Research, 1976
A new model of the near-surface geomagnetic main field and its secular variation has been derived. The main field part, a degree 12 spherical harmonic series of 168 internal source terms, was derived from 1248 representative values having a nearly even distribution over the earth.
Norman W. Peddie, Eugene B. Fabiano
openaire   +1 more source

A statistical model of the geomagnetic field

pure and applied geophysics, 1964
A statistical model of the geomagnetic field is derived, based on the assumption of an axial geocentric dipole field of strengthHe at the equator perturbed by randomly directed components of constant magnitudeh. The model fits the dispersions found from an analysis of the 1945 field, and the ratioh/He obtained for this field and from the palaeomagnetic
Edward Irving, Martin A. Ward
openaire   +1 more source

Positioning of the Ionospheric Field-Aligned Irregularities With Geomagnetic Field Model

IEEE Geoscience and Remote Sensing Letters, 2020
An observation model is introduced for accurate positioning of the ionospheric field-aligned irregularities (FAIs). The model is applied to the Hainan coherent scatter phased array radar (HCOPAR) in the Hainan island of China and constructed based on the International Geomagnetic Reference Field (IGRF) model.
Gang Chen 0026, Shan Yi, Zhihua Wang, Chunxiao Yan, Ting Yong, Han Jin, Wanlin Gong, Min Zhang   +7 more
openaire   +1 more source

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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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.
openaire   +4 more sources

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
openaire   +1 more source

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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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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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.
openaire   +4 more sources