地球自转及其和地球物理现象的联系：Ⅰ日长变化

EARTH ROTATION AND IT'S RELATIONS TO GEOPHYSICAL PHENOMENA:I.THE CHANGES OF LENGTH OF THE DAY

地球的自转运动（自转速率变化和地极运动）表征着地球的整体运动状况，以及地球各圈层地核，地幔，地壳，海洋和大气之间的相互作用过程，它们在维持总角动量守恒的条件下，形成了地球的动力学系统。在这个封闭的系统中，地球各圈层的力学过程和耦合作用以角动量交换的模式进行。因此，这个系统是一个典型的守恒系统，也是一个相互反馈的系统。本文回顾了近十年来的研究进展，分各个时间尺度讨论了日长变化及其地球物理激发原因，并评估未来十年内地球自转运动可能的研究方向及课题。

The rotation of the Earth, including variation of the rotation rate and polar motion , identified the statement of Earth's movement and the interaction between the discreted parts of the Earth, such as core, mantle, crust, sea and atmosphere. They make the Earth's dynamical system, the angular momentum of which is conserved. In this isolated system, the interactions between various parts of the Earth are acted in the form of the exchanges of angular momentum.So, this system is a typical conserved system as well as a inter-feedback system. This paper reviews recent progres in Earth rotation research and the current state of knowledge in the field during the period of last ten years. The excitation sources of the various time scales variations in the rotaion rate are described here together with anticipated advances and prospects for future.