A new method of gravity external correction for high precision gravity measurement

• Confusion of vertical datum will cause errors in gravity correction.
• Bouguer correction will lead to the destruction of tectonic feature.
• The method will overcome problems mentioned above and improve the correction precision.
• The method proposed in the paper is very efficient.
• Earth surface gravity anomaly can show more geology information.

There are a large number of simplifying assumptions in the external gravity correction methods in order to reduce the amount of calculation and improve the efficiency of operation. However, there are some problems caused by the simplifying assumptions, for example, errors in normal gravity caused by the confusion of ellipsoids, the indirect effect caused by the difference between the geoid surface and the ellipsoid surface, errors in the Bouguer correction caused by the improper selection of the density and destruction of structure caused by the Bouguer correction. In order to overcome this problem, we proposed a new method of gravity external correction for high precision gravity measurement. There are two steps in the correction method. The first one is to calculate the normal gravity of stations in any position with arbitrary latitude and geodetic height and then gravity anomaly is calculated by subtracting normal gravity from absolute gravity. The gravity anomaly to the position of station can be calculated instead of the gravity anomaly relative to the datum. Using some theoretical models and actual data in western China, we verified the gravity correction method proposed in the paper, and the result showed that the method can improve the accuracy and exploration effect of gravity exploration.