天文地球动力学中的相对论效应

Abstract

天文地球动力学利用空间与地面观测手段 ,监测和研究地球整体与各圈层的物质运动以及它们间的相互作用 ,这都离不开广义相对论涉及的时间与空间。随着空间对地观测精度的提高,为了充分利用高精度观测提供的信息,在天文地球动力学的研究中必须考虑相对论效应。所涉及的相对论效应包括:(1)相对论参考系的建立,(2)在恰当的参考系中对观测者和被观测对象的相对论运动方程(平动和自转)的描述,(3)观测者和被观测对象间的电磁信号传播,(4)依赖于坐标选择的结果与具有物理意义的可观测量间的转换,(5)某些基本概念与定义在广义相对论框架下的重新确认。本文对天文地球动力学中的这些相对论效应作了简要的评述。 Astro-geodynamics involves the measurement or monitoring of variation of spatial motion of the Earth as a whole and mass motion of each layers of the Earth, for instance the atmosphere, ocean, lithosphere, mantle and the core, using space-based techniques, and the study on their dynamic relation.The space and time which belongs to the realm of the General Relativity are concerned. With the rapid increase of space-based observational accuracy, the relativistic effects on the Astro-geodynamics must be taken into account to make full use of information of higher accurate observation. The relativistic effects concerned include (1) establishment of relativistic reference system; (2) relativistic equations of motion (translational and rotational) in an adequate reference system for the observer and the observed object; (3) propagation of an electromagnetic signal between the observed object and the observer, including the deflection of light,time delay of light, gravitational redshift, etc.; (4) conversion from the coordinate-dependent results into coordinate-independent ones of real physical meaning, such as proper direction, proper time; (5) clarification of some of the basic concepts and definitions, such as meaning of GM, definition of the astronomical unit, concepts of the ecliptic and the equinox.The principal relativistic effects on the Astro-geodynamics are briefly reviewed.