Study Of Refining Regional Geoid Based On Deflection Of The Vertical

The research of geoid determining is one of the basic issues of geodesy and geophysics. Deflection of the vertical is an indispensable quantity on the research of geoid determining. Geoid could be refined by the data of deflection of the vertical and gravity through least-squares collocation. The resolution of gravitational field and geoid model calculated only by satellite data is about 100-150 km. The resolution of gravitational field calculated only by gravity data is less than 20km. The gravitational information between 20km and 100-150km could be given by deflection of the vertical.In this paper, the differences of geoid undulations caculated using earth gravity model between geoid undulations caculated using deflection of the vertical are researched based on the recent earth gravity field EGM2008 to degeree 2160 released by the U.S National Geospatial-Intelligence Agency(NGA)。The data is 2.5'×2.5'resolution and 5'×5' resolution in mountain, plane and ocean. First, the geoid undulations of the three regions are separately derived by EGM2008. Then, deflections of the vertical of the three regions are separately derived by EGM2008, based on the topographical model ETOPO2V2g_i2_MSB.g98. At last, the geoid undulations of the three regions are separately derived from deflection of the vertical used Vening Meinesz formula and are computed with the model-based geoid undulation. The conclusion is:2.5'×2.5'resolution, the standard deviation of the differences in mountain is±0.311m, the standard deviation of the differences in plane is±0.218m, the standard deviation of the differences in ocean is±0.068m; 5'×5' resolution, the standard deviation of the differences in mountain is±0.468m, the standard deviation of the differences in plane is±0.328m, the standard deviation of the differences in ocean is±0.103m.