Investigations On Some Problems In High-Precision Quasi-geoid Determination

Gavity field is one of the basic physical fields in earth space. Physical geodesy is the science of the figure of the earth and of its gravity field. Along with the abundance of the earth gravity field model, gravity data in the earth surface, GPS/leveling data, DTM, satellite altimetry data, satellite gravity data (SST, SGG) and other related information of the earth gravity field, the determination of cm order geoid has been provided with necessary condition. In physical geodesy, because of the improvement of observation technique, people obtain kinds of boundary value in different type, for exmple, GPS/leveling on land, satellite altimetry on sea surface and satellite gravity gradient, and so on. At the same time, in the theory of boundary value problem, Stokes boundary value and Molodensky boundary value have developed by gravity-altimetry boundary value, gravity gradient boundary value problem, which are belong to over-determined boundary value problems.In the paper, based on the precision demand of cm order qusi-geoid, the data assimilation and precision assess in qusi-geoid refinement are systematically analyzed. And then, in order to solve the key problem in qusi-geoid refinement, a new method is presented which applies GPS/leveling height anomaly. In the paper, gravity potential model, gravity observation data in the surface of the earth, GPS/leveling and DTM are used to refine qusi-geoid. Firstly, the application of least square collocation technique in local gravity field is expatiated briefly. And then, the expression of experiential covariance function which is the kernel of least square configuration is improved. Finally, with regard to the application of GPS/leveling in qusi-geoid refinement and how to use GPS/leveling height anomaly effectively and reasonably, the paper presents the arithmetic of solving GPS/leveling over-determined boundary value problem.In the introduction of the paper, the research development and background in qusi-geoid refinement are introduced simply. Besides, the actual problems in qusi-geoid refinement are analyzed. The structure of the paper and resolved problems are introduced finally.In chapter 2, the basic theories in qusi-geoid refinement are described briefly. For example, Stokes boundary value problem, Molodensky boundary value problem, remove-restore technique and sphere hat method. The method of least square collocation will be expatiated particularly in chapter 3 while the structure of first order item and secondary order item in Molodensky series are in chapter 6 combined with local terrain.Chapter 3 is one of the important content in the paper. Firstly, statistical correlative quantities in physical geodesy, together with the application of least square configuration in qusi-geoid refinement are explained briefly. Then, combined with spherical-harmonic spread formula and Tscherning/Rapp experiential covariance function, a new covariance function estimation method is created, whose configuration capability is tested and analyzed.The error analysis of qusi-geoid is done in chapter 4. With the data and local gravity field arithmetic in qusi-geoid refinement, the chapter analyzes the error effect characteristics from different type data fountain, provides simply error spread connection and error effect of Stokes truncation error and reference potential model based on truncation theory.Chapter 5 is the other important content in the paper. People have accepted high precision height anomaly and geoid undulation provided by GPS/leveling. Also, GPS/leveling has been applied in qusi-geoid refinement. In order to apply GPS/leveling more effectively and more...