地球自转及其和地球物理现象的联系：Ⅱ地极运动

EARTH ROTATION AND IT'S RELATIONS TO GEOPHYSICAL PHENOMENA -Ⅱ POLAR MOTION

地球自转运动包括岁差和章动，极移和日长的变化。极移指自转轴相对地壳的运动。其主要激发原因是地球上物质分布的变化。因而，对极移的观测和研究必然为全球性的地球物理现象提供着信息。极移按时间尺度可分为长趋势变化，Ｃｈａｎｄｌｅｒ摆动，季节性摆动以及快速极移。本文回顾和综述了这个课题的研究成果。并估计了九十年代后期可能的研究方向。

The rotation of the Earth includes precession, nutation, variations of the rotation rate and polar motion. Polar motion is the movement of the rotation axis with respect to the crust. The polar motion excitation is dominated by mass redistributions. Therefore,observation and research of the polar motion can provide information about global geophysical processes.This paper reviews recent progres in the polar motion research and the current state of knowledge in the field. On time scales, the secular, Chandler, seasonal and rapid variations in polar motion can be observed. The excitation sources of the polar motion are described here together with anticipated advances and prospects for the future.