摘要
运用已经发展起来的共振激发和参数共振模型，在频率调制的基础上，对IERS极移数据测算出钱德勒摆动的Q值，得到平均值为63，并以每百年0.8的速率在增大。这一结果与Q的滞弹性PREM模型理论值69十分接近，表明共振激发模型和参数共振模型完全与钱德勒摆动滞弹理论相容。
Former dynamical equations of Chandler wobble did not intreduce damping attenuation index. Therefore, it says that Q of Chandler wobble can not be easily specified directly from poar motion data. A resonance excitation medel is intreduced, which provides the reason that CW amplitude reserves an adequate level. And later, the resonance excitation medel is developed into a parameter resonance one. The pararneter resonance medel shows that CW amplitude oscillates high in long peried. In this paper, Q of Chandler wobble is easily specified from IERS polar motion data using the developed resonance excitation medel. But since in resonance excitation medel the damping index is linear, Q of Chandler wobble specified from the data shows a little small.Then frequency medulation is intreduced. The frequency and damping parameter in the resonance excitation equation become as time-dependent parameters. Parameter resonance medel can provide a revision of visco-elasticity for computing Q. Then the mean value of Q is 63, which is increasing slowly at the rate of 0. 8 every secular Peried. This result is very much identical with the theoretical Q result of 69 under visco-elastic PREM model. It shows that parameter resonance model is exactly appropriate with the visco-elastic theoretical model. The long time tendency of Chandler wobble is figured out. Frequency medulation can be seen and analyzed spectrally. Time series of attenuation index is provided and time series of Q shows a very stable result in the figure.
出处
《武汉测绘科技大学学报》
CSCD
1999年第4期351-354,共4页
Geomatics and Information Science of Wuhan University
关键词
钱德勒摆动
极移数据
共振激发
天文大地测量
Chandler wobble
IERS polar motion data
resonance excitation
parameter resonance
visco-elasticity
