Research In A High Accuracy Local Geoid

The purpose of determining high accuracy local geoid . one is to develop physical geodesy ,the other is to solve the problem that trigonometric leveling and low accuracy leveling can be superseded by GPS surveying in one to ten thousands (or above)basic scale map surveying .So the field work and the production cost will be reduced ,and the advantages of GPS surveying ,such as convenience ,better precision ,higher efficiency , lower cost and so on ,will be utilized in surveying and mapping .The article discusses to derive the high accuracy geoid in the method of gravity (stokes formula and, molodensky theory) and GPS leveling. By using surface gravity data, thirty seconds by thirty seconds resolution DEM, global gravity model (EGM96, WDM94), stokes formula and, molodensky theory, remove_restore , FFT technique and appropriate software,in comparison with a series of calculations ,the local gravity geoid is determined at first .Then the local geoid is combined with height anomaly control network obtained from GPS leveling .Finally the local geoid with plus or minus ten centimeter accuracy and 2.5minutes by 2.5 minutes resolution is derived. The software to calculate the normal height by GPS geodetic height will be in the surveying.The local geoid have been examined .The examination results demonstrate that the accuracy of the geoid is reliable .At the same time, a functional software is presented, and the local geoid has been successfully applied in surveying and mapping.