我国大地坐标系的换代问题

首先指出了我国现有大地坐标系在先进性和实用性方面存在的问题，提出了我们面临的选择与采用地心坐标系的建议，然后就地心坐标系的定义和实现、参考椭球常数、正常重力公式等问题提出了初步意见，并就坐标系改变对旧地形图的影响问题进行了研究。我国大地坐标系应由局部坐标系更新为地心坐标系。我国大地坐标系的定义应与IERS(国际地球自转服务)协议相一致，采用国际常用的参考椭球和正常重力公式。本文提出的参考椭球和正常重力公式符合这些原则，提出的地形图坐标系变化改正方案应是基本可行的。

National Geodetic Coordinate System:To Next Generation

In this paper the problems of the national geodetic coordinate system are pointed out in terms of advanced character and practicability,the choices of the coordinate systems are put forward and the adoption of a geocentric coordinate system are proposed.Then the opinions are given on the definition and realization of geocentric coordinate system,the constants of reference ellipsoid and the normal gravity formulas.Finally the influence of the change of coordinate system upon the old topographic maps is studied.The main conclusions are drawn as follows:the existing national coordinate systems have failure of their advanced character;they have increasingly failed to fit in with the needs of national economic construction and national defence construction and with the development of space technology;the geocentric coordinate system can fulfill the scientific and practical demands of the geodesy,aerospace science and technology,geoscience study,navigation etc.;the national coordinate system should be updated to the geocentric from the local system;the definition of the national geodetic coordinate system should be consistent with IERS conventions;the adopted ellipsoid and normal gravity formulas should be in common use internationally.The proposed ellipsoid and the formulas conform to these principles.Furthermore the proposed scheme of the old topographical map correction for the change of coordinate system should be basically feasible and practical.