Lan New Line The Banded Region EGM2008Model Applicability

The emergence of highly precise Earth gravitational model EGM2008not only providesan unprecedented prospect for the accuracy analysis work of global geoids and a new methodto obtain the elevation abnormality but also provides a new way to convert normal elevation.To the GPS measurement technology in practical engineering applications, with the help ofEGM2008, China eastern and western unbalanced gravity situation has been improved. Inpractical engineering applications, the model can be used to convert GPS height into normalheight and its accuracy can achieve decimeter or centimeter level. What’s more, the modelsees the future of GPS measurement instead of leveling.As one active research of modern physical geodesy, a major breakthrough has beenachieved in the accuracy and resolution of global and local gravitational model, especiallybecause of the improvement of ground and airborne gravity measurement techniques and theparticipation of new satellite gravity measurements, the world’s most advanced gravitationalmodel EGM2008has reached decimeter or even centimeter level. Local and globalgravitational model can analyze the Earth’s gravity field, so that it can make calculating thegeoids, deflection of the vertical line, gravity anomalies, gravity disturbances and otherparameters of the gravity field convenient and fast, based on the theoretical and practicalapplication advantages, local and global gravitational model has a very promising future ingeodesy, geophysics, geodynamics, oceanography, space science,military applications andother disciplines and fields.This paper first introduces the definition and connotation of Earth gravitational model(EGM2008), and then sets forth the basic theory of the GPS height conversion andconventional GPS leveling fitting mathematical functions, in addition, elaborates model GPSheight conversion principle based on EGM2008, and most importantly the paper also involvesremove-restore principle used in the current high accurate GPS height conversion based onEGM2008model. The illustrating case has been selected as the project of Ledu area ofLanxin Second Railway, the data gained by using GPS measurement tests applicability ofEGM2008model in the survey area:(1) EGM2008has been put into contrast with EGM96model in the aspects of the absolute and relative verification program to detect its accuracy;(2)use different access points in the region in view of EGM2008model to detect its accuracy andapplicability. In addition, the fitting method of function model and remove-restore based onEGM2008are both taken to analyze the accuracy of the remove-restore and the applicabilityof EGM2008in some strip region of Lanxin Second Railway.