| The complete Bouguer reduction includes, in addition to the height correction, both the latitude and terrain correction. In mountainous areas, the topographical effect of the area around the computation point is differential. If neglecting the topographical effect of the terrain reduction, the interpreters may be obtain the data including much false anomaly ,and the image of anomaly can be obviously distortion. So, the decision of interpreting may be affected. With the error of gravity meters becoming smaller and smaller, the availability of improved terrain and geoid databases, enhanced computational power, and increasing use of global positioning system (GPS) technology to establish the location and heights of gravity stations, in rugged topography terrain corrections are the most important source of error in the reduced Bouguer anomalies Therefore, the available reduction procedures are not be satisfaction for demand. As more accurate gravity anomalies have become of interest, the modifications to reduction procedures are important.The topographical reduction procedures can be divided into planar ,spherical and ellipsoidal terrain corrections. When the topographical surface of the earth is very smooth, and the exploratial areas are very small , planar methods are high accuracy. But, in regions of rugged topography, and in areas of thousands of kilometers or longer, we must be use the ellipsoidal reference. Because of using different reference surface, the terrain correction results may be different and the geophysical indirect effect can be producted. Using the GRS80 ellipsoid as the vertical datum , it directly uses GPS heights relative to the ellipsoid without the need to correct for geoidal deviations that may be inadequately determined. the GRS80 ellipsoid is one single internationally accepted reference ellipsoid.Today, gravity exploration worked in mountainous areas, both areogravity survey and satellite gravity application need a great of data. So this text develop the software of the ellipsoidal terrain correction methods using the tesseroid modelling, and obtaining good result. |
