The effects of the atmosphere and oceans on the Earth's wobble and on the seasonal variations in the length of day — II. Results

Summary. The two most prominent features of the Earth's wobble spectrum are the annual wobble and the 14 month Chandler wobble. The annual wobble is generally believed to be driven by seasonal effects in the atmosphere, in the oceans, and in the global distribution of fresh water, although good quantitative agreement has remained somewhat elusive. The primary source of Chandler wobble excitation is uncertain. Here, we examine the effects of the atmosphere and oceans on wobble excitation. Where data are insufficient we rely on dynamical models. We get good agreement with the astronomically observed annual wobble excitation. On the other hand, we find that although the atmosphere and oceans had a noticeable effect on the Chandler wobble excitation during 1900–1973, they were apparently not the primary excitation source. We also consider the role of the atmosphere and oceans in maintaining the semi-annual and annual variations in the length of day. Our estimates disagree with the results of previous studies by about 10–20 per cent.

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