Radial dipoles as the sources of the Earth's main magnetic field

摘要: It is assumed that magnetic dipoles are useful as a first approximation to the electrical currents in core produce earth's main field. For simplicity model restricted central dipole and several additional radial at equal distances from center of earth. A least-squares method used adjust amplitude, latitude, longitude each for best fit observed field components on surface. In four studies was United States 1945 world charts. Originally 11 dipoles, 10 them core-mantle interface 0.54 earth radii, were used. Progressively better fits obtained placed deeper, two eliminated greater depths. The 29-parameter, 9-dipole model, with 0.28 produced nearly good Vestine's 48 spherical harmonic coefficients. Models also fitted 1955 chart field, British Admiralty synthesized Finch-Leaton coefficients 1955. last fit. In all cases surprisingly deep considerably stronger than centered given by three great depth qualitatively explained shielding effect mantle core. analyses Vestine Finch Leaton compared computed parameters.