Repeated Gravity Observations To Study Changes In Hexi Area Geoid

The geoid is the essential characterization for the earth shape in the geodetic science research and application field. It is thought as the origin of level surface in the geodesy. The precise geoid plays an important role in exploring the globe tectogenesis and ocean environment as well as submarine topography. We could improve the height precision and research the substance movement of the interior earth, when study the geoid changes.In this paper, the formula which calculates the geoid changes is deduced by the repetition gravity measurement, the theory and method about which the repetition gravity measurement be transformed to the geoid is discussed. He-Xi geoid's changes is calculated and researched with the gravity variation data in the period from 1992 to 2003. This paper uses the same point repetition gravity measurement difference in calculating the geoid changes model, avoiding the complex gravity transform, and providing a new way to research the earth deeps tectonic by using the geoid distortion.