中文摘要：

研究了三轴地球的自由晃动,给出了Euler动力学方程的椭圆函数解和Euler/Chandler周期。研究表明,三轴性使得极移轨迹变为短、长半轴分别与主惯性轴A、B平行的椭圆,同时使得极移和自转速率产生耦合效应,导致Chandler晃动的振幅-频率调制机制。根据IERS数据还得出了地极正以3.93 mas/a的速率向77.98°W方向漂移的结论。

英文摘要：

We study the theory of free wobble of the triaxial Earth and find that the Euler period should be actually expressed by the complete elliptic integral of first kind and the trace of the free polar motion is elliptic and the orientations of its semi-minor and major axes are approximately parallel to the Earth＇s principal axes A and B, respectively. Due to the triaxiality of the Earth, there is a mechanism of the frequency amplitude modulation in the Chandler wobble which might be a candidate to explain the correlation between the amplitude and the period of the Chandler wobble. We compared the theoretical polar parameters （m1, m2 ） with the observed values for the Chandler components obtained from the data EOP （IERS）, and find that they coincide with each other quite well, especially in recent years. Moreover, a polar wander towards 77.98°W at the rate 3.93 mas/a was also obtained from the IERS data.