Building Of An Ultra-high-degree Geopotential Model

This dissertation focuses on the theory and methodology of ultra-high-degree geopotential modeldetermination.With the development of satellite-gravimetry technology and thanks to the globalhigh-resolution terrestrial gravity data, it’s possible to establish a high precise ultra-high-degreegeopotential model of d/o2160. The main works are listed as follows:1The main methods about recovery of the earth gravity field are analyzed, also themethods to build the global merged5’×5’ mean anomaly file.2A lot of computing methods of the fully normalized associated legendre function aredetailedly discussed. Advantages and disadvantages of these methods are compared in threeaspects: numerical efficiency, numerical precision and arithmetic overflow. A set if improvedalgorithms used for harmonic analysis of very high degree and order are analysed, which solvethe problem on arithmetic overflow.3The FFT is derived and used to improve the numerical efficiency of building geopotentialmodel and the computation of model gravity anomaly.4Least squares method，numerical quadrature method and regional integral correction forsolving earth’s gravity field model from gravity anomaly is summarized and Block-DiagonalLeast-Squares Approach used in EGM96and EGM2008is studied in detail.5Frequency weight combined method is used to combine the earth’s gravity field modelfrom global5’×5’ merged gravity anomaly with satellite-only model.6Use torus harmonic analysis approach to build an ultra-high-degree geopotential modelwith a global5’×5’ merged gravity anomaly file which is developed by ourselves and themodel is proved as well as EGM2008in chinese area. With the use of global5’×5’ grid ofgravity anomaly data builded by our own, I build two relatively independent ultra-high-degreegeopotential models CSnm₁and CSnm₂. we use1007GPS/leveling points and889independent astronomical geodetic vertical deflections of China witch is located uniformly to dothe exterior checking of models above. The model geoid from CSnm₁and CSnm₂are as wellas the geoid from EGM2008and the standard-deviation of the geoid discrepancy can reach30cmafter outlier detection, also the model vertical deflections from CSnm₁and CSnm₂are betterthan that from EGM2008and the standard-deviation of the vertical deflections discrepancy canreach2.2after outlier detection, witch is0.5lesser than EGM2008’s discrepancy.