Comparison between simple and complete Bouguer approaches in interpolation of mean gravity anomalies

Abstract

The determination of the geoid, which is a real shape of the Earth, with an accuracy of 1 cm is one of the most important aim of the today’s geodetic community. The gravimetric geoid modeling is the most preferred technique in order to reach to this target. Nevertheless, the gravity values measured on the physical surface of the Earth can not be directly included to this process. First of all, surface gravity values should be reduced to gravity anomalies and, during this step they should not lose their topographic features of the Earth's surface where the data is collected. On the other hand, in order to generate gravity anomalies on a regular grid, it is expected that dependency of gravity anomalies (to be used asreference data in interpolation) to local topography should be minimum. While free-air anomalies are the basic data source for determining the geoid, Bouguer anomalies describing the smoother Earth’s shape, are convenient to the interpolation of gravity anomalies. Therefore, the dependence of Bouguer gravity anomalies, which is a main data in the interpolation procedure, should be reduced to minimum. Although the simple Bouguer anomalies are preferred in practice, it is known that they contain more or less the negative effects of irregular topography. In this study, the differences between simple and complete Bouguer anomalies are presented in a test area. It is seen that the differences between free-air anomalies derived from both approximations are numerically increased up to16 mGal, correlated with the topography. This result indicates that complete Bouguer anomalies should be used in interpolation process in regions posing irregular topography, such as Turkey.