The Statistical Properties Of The Polar Motion And Atmospheric Excitation Compared

The theory of rotation of the Earth is discussed and the achievements in the research of the rotation of the Earth and its excitation are reviewed. Furthermore, we briefly introduce the effective atmospheric angular momentum function and the atmospheric angular momentum data. Several data process methods adopted in our work is presented. We performed a simulative test, which confirms that wavelet analysis can separate annual wobble and Chandler wobble. Our results show that this method can be used in astronomical geodynamies effectively. This paper is divided into two parts. The first is about statistic characteristic of polar motion. Polar motion includes secular motion, long period fluctuations, Chandler wobble, annual wobble and high frequency wobble. The secular motion is 3.4mas/year and towards 760W meridian. Long period fluctuations have difference periods in x-axis and y-axis. They are 31.7-year and 24-year in x-axis and 28.5-year and 22.9-year in y-axis. These 2~? decades fluctuations have an amplitude of about 30 mas , and are very nearly linearly polarized, with the observed motion of pole being almost entirely along a line between 360E and 1440W. There is a 55.4-year wobble whose amplitude is 9 mas. The amplitude of the interannual fluctuations is about 4? mas. The amplitude of long period fluctuations decreased after 1970. The annual wobble is a steady wobble. It retrograde wobble is only 1/20 of prograde wobble in amplitude. The amplitude of Chandler wobble has large variable range from 0?09 to 0?28. The amplitude of x-axis is almost the same as that y-axis. The comparison between inferred excitation(z? and AAM excitation(z~) is presented in the second part. There seems no peaks in high frequency of the spectrum of both inferred excitation and AAM excitation. Our results suggest that there is a good correlation between the two excitations in high frequency. But the amplitude of is only a half of that of z . Therefore it is shown that the atmosphere is the main excitation of polar motion in high frequency.