Meteorological Excitation of the Earth's Wobble

Abstract

The objective of this paper is to examine the seasonal variations in the oceans and atmosphere that force the Earth's annual wobble, and to determine whether motions of air and water are a significant source of Chandler-wobble excitation. Although our investigation is similar to the one undertaken by Munk and Hassan over 15 years ago, we come to entirely different conclusions, largely because of differences in the details of our analysis. We find that the oceans and atmosphere are not observed well enough to fully explain the annual wobble, although much of it can be accounted for by annual changes in atmospheric mass distribution and continental water storage. Near the Chandler frequency there is evidence of significant coherence between polar motion and atmospheric pressure observations for the years 1901 and 1970, suggesting that the atmosphere is important in maintaining the Chandler wobble. The magnitude of meteorological variation appears to be large enough to account for more than half, and perhaps most of the Chandler wobble variance.