关于重力勘查的高度改正应采用何种高程系统的讨论

重力勘查的观测值必须进行正常场与高度改正,为此要测量重力测点的平面位置与高程,尤其对高程测量精度要求甚严。以前测地工作使用经纬仪、水准仪和测距仪等,高程系统按“规范”(1)采用大地水准面的“正高系统”.近来全球卫星定位系统(GPS)开始应用于重力勘查中,GPS测量的高程为WGS-84的“大地高系统”,这样需要把“大地高”换算到“正高”.这样做即要花费许多工作量,又会增加换算中产生的误差。本文通过对地球正常重力场理论公式的分析,认为可以采用GPS测量的大地高进行重力高度改正。

A DISCUSSION ON THE SELECTION OF ELEVATION SYSTEM IN ALTITUDE CORRECTION OF GRAVITY SURVEY

The observed values of gravity survey must undergo normal field and elevation correction. Therefore,the plane positions and elevations of gravity measuring points must be measured; the elevation survey, in particular,must be very precise. In theodolites, surveyor's levels and range finders used previously for geodesic work, the “normal elevation system” of geoid surface was adopted for the elevation system on the has of “specifications”. In recent you, the Gladal Positioning System (GPS) has been introded into gravity survey, and the elevation of GPS survey is “geodetic elevation system” of WGS-84, so that the “geodetic elevation” must be converted into “normal elevation”. This conversion requires considerable amounts of work and adds to possibilities of errors. Based on analysing theoretical formula of normal gravity field of the earth, the author holds that the geodetic elevation of GPS survey might ha adopted for cavity altitude correction.