© Unknown
Motion of the earth's liquid core, the so-called geodynamo, generates its magnetic field. Gauthier Hulot of the Institut de Physique du Globe de Paris and his colleagues used satellite data recorded 20 years apart to track changes in this field. In two regions of the boundary between the earth's core and the overlying mantle, the researchers detected a reversed magnetic field. In a section lying beneath the southern tip of Africa, the magnetic field points toward the center of the earth opposite to the dominant outward-pointing field of the Southern Hemisphere. And a second congregation of reversed-flux patches exists near the North Pole. Having modeled the growth and movement of these inverted-flux sections, they can now account for nearly the entire decrease in the main dipole field of the earth over the past 150 years.
