Geomagnetic parameters derived from an analytic description of the Earth's magnetic field.
Abstract
A recent geomagnetic model containing 720 trend and trigonometric coefficients represents each spherical harmonic coefficient as a continuous function of time which exactly duplicates the IGRF coefficients at the nine IGRF epochs (1945 to 1985 at five year intervals) and allows a reasonable prediction five years beyond the last epoch. Use of this model permits time derivatives of magnetic elements and other derived quantities to be taken so that a detailed look at several geomagnetic parameters vs time can be obtained. It is shown that from 1945 to 1985 the quadrupole field contributed 2.6 times more power to the secular variation field on the surface of the earth than the dipole field. It is also shown that the rootmeansquared surface field shows a strong periodicity which may be related to the solar cycle. This apparent solarcycle effect diminishes with time as more satellite data are used indicating that an appreciable part of it may be caused by noisy data and a poor distribution of data for a couple of decades following World War II.
 Publication:

Journal of Geomagnetism and Geoelectricity
 Pub Date:
 1988
 DOI:
 10.5636/jgg.40.207
 Bibcode:
 1988JGG....40..207A
 Keywords:

 Geomagnetism;
 Harmonic Analysis;
 Spherical Harmonics;
 Magnetic Variations;
 Secular Variations;
 Solar Activity Effects;
 Solar Cycles;
 Geomagnetic Field:Models