Evaluation of Global Gravity Field Models by Using GNSS/leveling Data: a Case Study in Vietnam

The assessment results of the accuracy of the global gravity field model from the measured data of 816 GNSS/leveling points through 05 global gravity field models EGM2008, EIGEN-6C4, GECO, XGM2019e_2159, SGG-UGM-2 in three regions: North, Central, South, and Vietnam territory, shows that the different values of height anomaly among five models for three regions are not significant and do not follow any rule. Accuracy between models at later stages is often higher than in previous stages. The analytical results have determined that the accuracy of the global gravity field model XGM2019e_2159 is the highest in the regions: North, Central, and Vietnam territory; the Global gravity field model EGM2008 is the lowest in all three regions and Vietnam territory. The average accuracy of the global gravity field model EIGEN-6C4, GECO, SGG-GM-2 is about ± 0.1667 m for Vietnam territory; the accuracy of the global gravity field model XGM2019e_2159 is ± 0.1460 m. The analytical results show that the model XGM2019e_2159 is the most suitable for building high-accuracy quasigeoid models in Vietnam territory.