The Terrain Correction Calculation Of Airborne Gravity And The Improvement

Airborne gravity is simpler, faster and more economical geophysics method compared with conventional gravity survey. Like other geophysical methods, it’s necessary to process the field data of airborne gravity to abstain the information that reveal the underground mass distribution, and his will ensure the inversion and interpretation is correct. The terrain correction is one of the important steps to get airborne gravity Bouguer gravity anomaly, however, it is considered problem which with a lot of trouble to conducted. So it’s significant to study the terrain correction of airborne gravity.In this thesis, the airborne gravity theory is described based on the comparison with the terrain correction of earth surface gravity exploration. The airborne gravity 3D terrain correction formula is given and how it is come from is deduced step by step. The terrain correction core calculation is achieved through FORTRAN language, and the interface is build through C# language which makes the terrain correction process more easy and convenient. A series of models from a simple block to complicated true terrain are designed to test this process. During the research, a phenomenon is found that the lager the maximum correction radius is, the better the calculation result is.On that basis, a further study is done to see the relationship between the maximum correction radius and the calculation accuracy. The required precision will be reached in the following condition: the terrain effect from the outside of the maximum terrain radius is less than 0.20mGal. How the gravity effect is changed with the elevation and distance of one terrain cell is considered, and how it is changed with the maximum correction radius and elevation is obtained too.Because of the terrain range is large inside the maximum correction radius and so is the amount of the calculation of terrain correction, a more rapid method is needed. In this thesis, the adaptive quadtree method is applied in the airborne gravity terrain correction. This improvement will comprehensively consider the distance and elevation of the terrain cell, and pick up the calculation speed without the loss of accuracy. A gauss surface hill is designed to test the accuracy of the adaptive quadtree airborne terrain correction method, the calculation results meet the accuracy demand, but the time consumed is 7.6% of the former method. The adaptive quadtree method is really feasible in the airborne terrain correction.