A PECULIAR PROPERTY OF GEOMAGNETIC FIELD

Characteristics of the geomagnetic field are shown by plotting equivalent current functions J on successively deeper spherical surfaces within the earth. As the depth increases, the amplification of the higher-order spherical harmonic terms increases, so that, in effect, higher-order terms successively are brought into focus. Maps of J reveal that negative extrema of J are much more prominent than positive extrema and are equally so in the northern and southern hemispheres. Coriolis forces are surely important in the generation of the earth's magnetic field. Since the Coriolis forces are of opposite sign in the northern and southern hemispheres, we have to seek a second factor that changes sign between the two hemispheres. It is suggested that this factor implies a general circulation pattern in the core that is antisymmetric between the two hemispheres. Copyright 1968 by the American Geophysical Union.