Geodynamo Turns Toward a Stable Magnetic Field

JAN 01, 1996

Supercomputer simulation shows 4 that fluid motions in Earth’s core could sustain the geomagnetic field. Geophysicists are excited—and also a little relieved; such a “geodynamo” has been the only plausible explanation for geomagnetism for more than 40 years.

DOI: 10.1063/1.2807456

Ray Ladbury

Earth’s magnetic field has been a subject of curiosity for at least 3000 years and of quantitative study for more than 400 years. Geologic samples now extend our knowledge of geomagnetism back billions of years, and satellites and observatories log the tiniest changes in the strength and direction of the geomagnetic field. these investigations have revealed many intriguing characteristics of geomagnetism that any successful model of the phenomenon must explain—such as the stability of the geomagnetic field on time scales of $10^{5}$ years, the field’s predominantly dipole nature, the offset of its dipole axis from Earth’s rotational axis, its temporal variability and so on. All these geomagnetic observations, however, have done little to suggest what a model of geomagnetism should look like.