Determination of Geoid Height at the Summit of Mount Qomolangma
Objectives:The determination of the orthometric height of Mount Qomolangma requires the prior calculation of geoid height,which is determinined by the quasi-geoid(height anomaly)and the height difference between the quasi-geoid and geoid.Methods:First,based on Molodensky principle and remove-restore technology,a 1.5'× 1.5'gravity quasi-geoid model in Mount Qomolangma region can be established by using a terrain model,an earth gravity field model,and the fusion data of ground and air-borne gravity.Then,system errors can be eliminated by correcting the gravity quasi-geoid model with GNSS-leveling points.The quasi-geoid based on the National Vertical Datum 1985 can be obtained.Final-ly,the height difference between the quasi-geoid and geoid can be calculated by using the remove-restore method by gravity at the summit of Mount Qomolangma.Results:The results show that the EIGEN-6C4 earth gravity field model performs best in the region of Mount Qomolangma compared to EGM2008 and XGM2019e_2159.The precision of the gravity geoid model is 7.8 cm based solely on the EIGEN-6C4 and ground gravity data,while it is 4.8 cm based on the EIGEN-6C4 and the fusion data of ground and airborne gravity.The accuracy of model is improved by approximately 40％than using ground gravity data only.At the summit of Mount Qomolangma,the height anomaly is-25.586 m,the height difference between the quasi-geoid and geoid is-1.216 m,and the geoid height is(-26.802±0.06)m in the National Height Datum 1985.Conclusions:Airborne gravity can effectively provide data for the region where ground gravity data is sparse or non-existent.By incorporating airborne gravity,the density of gravity data at the summit of Mount Qomolangma has been greatly improved,leading to an increased accuracy of the quasi-geoid model.The availability of richer data,more accurate models,and more advanced calculation methods in 2020 resulted in more reliable results compared to the 2005 measurement.
Mount Qomolangmaairborne gravityquasi-geoidremove-restore methodgeoid height
NETL
NSTL
万方数据
