The excitation of the Earth's polar motion
Reporter : Wei-Yung Chung
Abstract
The motion of the Earth's rotation axis with respect to the geographical reference frame, known as the polar motion, has been observed for more than a century now. Barnes et al. (1983) and Hide (1984) examined some aspects of the underlying theory of non-rigid body rotational dynamics and angular momentum exchange between the atmosphere and solid Earth. They demonstrated that meteorological phenomena provide an important contribution to the excitation of polar motion. Their work offered a theoretical basis for future routine determinations of atmospheric angular momentum fluctuations for the purposes of meteorological and geophysical research. However, Chao (1985) pointed out a fundamental flaw in their comparison processes, in terms of the difference in integration approach versus the integration approach. He reached the conclusion that the integration approach is misleading, and demonstrated that by numerical experiments. Finally, we shall show a digital convolution equation to generate a polar motion series from excitation axis displacements, or conversely for inferring the excitation axis displacements from observed polar motion by deconvolution.
Reference
Hide, R., 1984. Rotation of the atmospheres of the Earth and planets, Phil. Trans. R. Soc. Lond., A 313, 107-121.
Chao, B.F., 1985. On the Excitation of the Earth's Polar Motion, Geophys. Res. Lett., 12(8), 526-529.
Wilson, C., 1985. Discrete Polar Motion Equations, Geophysical Journal Royal Astronomical Society, 80, 551-554.