Definitions of the geomagnetic equator

Abstract

Different models of equators are exposed and the advantages of the equator defined by a normal plane to the dipole located in the magnetic terrestrial centre C are shown. The geomagnetic equator has a great interest in a number of geophysical problems. Magnetic charts with isoclinal curves are constructed with data obtained from observations of terrestrial magnetism. The real magnetic equator will he defined by the curve of minimum inclination, which is very irregular to be mathematically determined and considered in the physical models for other studies. In particular, the physicists doingwork on cosmic rays on which the magnetic field exerts an influence, have considered that the geomagnetic equator should be determined by minimal radiation points. Not only the curve would also be irregular, but these is also the inconvenience of lack of data for its study. When this paper was presented in the Mathematical Congress of the Mexican Mathematical Society, in the city of Merida, in September of 1960, there was unawareness of any publication on the empirical curve of cosmic radiation. In 1961, at the Postdam Geomagnetic Institute a graph was prepared in which that the cosmic ray equator, approximates the minimum inclination equator: Z = 0 (Fig. 1).