The Theory And Application Research Of Refining Regional Geoid

The geoid is an important physical reference surface to describe the shape ofthe earth, is one of the geodetic datum. Refining the global and regional geoidconstantly, it is a long-term strategic task of geodetic surveying. With thedevelopment of the geoid technology, establishing high-precision, high-resolutionregional geoid requires not only the GPS technology and standards of measurementtechniques, but the Earth’s gravity field of modern theories and methods is alsoessential, in short, it has important scientific significance to establish a regionalquasi-geoid with modern technology.To begin with, the article analyses the developments of refining regional geoidin China and abroad, focusing on the development and existing results of regionalgeoid in China. On the geoid refinement are summarized, the article introducestheoretical basis of geoid refinement, that are, different vertical system and the dateof the corresponding datum. Then it studies systematically the basic theories andprinciples of refining regional geoid and digs into the methods of geometer andgravity respectively. In the geometrical method, it introduces three methods,GPS/leveling, astronomy leveling and satellite altimetry. It especially describesGPS/leveling fitting methods: the weighted average fitting, curve fitting(multinomial curve fitting and Akima curve fitting) and curved surface fitting (hardyfunction interpolation fitting). Respectively with the same data as an example, usingweighted average fitting method, multinomial curve fitting method and curvedsurface fitting method to the actual fitting arithmetic, the fitting effect andpracticability of the respective methods are compared, the useful conclusion areobtained. it also analyzes the error resources of regional geoid refining. In the gravitymethod, it describes the theories (Stokes formula and Molodensky theory) andtechniques (remove~restore technique,2DFFT technique) in determining a preciseregional geoid, the computing model of geoid, means of determining regionalcentimeter rank accurate geoid. Beside，The author also studied the standard model of the Earth’s gravity field and topographic correction model with GPS data. Thetheory and implementation steps of refining the geoid are presented with removal一fitting一the restoration. Through specific examples, the accuracy and practicabilityare compared, thus obtaining some significant conclusions.At last, the paper summarizes the work and proposes some considerations andways to improve the regional geoid refinement.