ON THE GEOPHYSICAL INTERPRETATION OF IRREGULARITIES IN THE ROTATION OF THE EARTH

Abstract

Astronomical observations have indicated that variations in the Earth's rotation by several parts per hundred million sometimes occur over periods of one or two decades. These irregularities may be caused by variations in the distribution of matter, or by variable motion relative to the Earth. It is found that processes in the atmosphere and ocean are inadequate to account for all of the observed irregularities, but that their effect is not necessarily negligible. Processes in the crust and mantle could barely do so, but such processes seem highly unlikely for a number of reasons. The irregularities can be accounted for by a variable motion in the core amounting to a fraction of the total motion indicated by the westward drift of the Earth's magnetic field.