Study On The Methods Of Refining The Quasi-Geoid Based On EGM2008

Refining geoid is one of important issues in fields such as geodesy and geophysical as well as an important basic survey project. Regional geoid determination with high precision is the research hotspot of modern geodesy. It is of great scientific significance and pratical application value to determine a regional quasi-geoid with high-precision, high-resolution by GPS technology, leveling, modern theories and methods of the Earth gravity field determination.At first, the paper describes the basic theories, principles and theoretical knowledge of precise determination of local geoid, and then the theory of the Earth gravity model and Chinese Quasi-Geoid2000are analyzed. Finally, implementation steps of refining the geoid with the Earth gravity model and GPS/leveling data by the remove-restore technique are mainly studied. According to the exsiting problems that gravity data, digital elevation model are very difficult to obtain in China; EGM2008can only calculate model geoid height.The method of refining the geoid with the new remove-restore technique based on model geoid height calculated by EGM2008is studied. The quasi-geoid determinations of the three regions by this method reach centimeter-level presicion. By comparing the fitting results based on EGM96, the presicion of refining quasi-geoid used the remove-restore technique based on the model geoid height calculated by EGM2008is higher and can also achieve common leveling precision. It has been realized that the geoid is refined based on gravity field model without gravity data. It is of great significance and application value to refine local area geoid as soon as possible, for gravity data are difficult to obtain in China.