An analytical description of the magnetic field of bygone epochs, and a determination of the spectrum of magnetic waves in the earth's core

An approximate analytical representation of the fundamental geomagnetic field over the last 1500 years is given in the form of a superimposition of a small number of running waves. The field approximation may be interpreted as the representation of variations in the geomagnetic field in the form of the superimposition of fields connected with magnetic waves propagated in the earth's core. The wave spectrum obtained is examined. An estimation is given of the toroidal field in the earth's core.