Determination of the geopotential value on the permanent GNSS stations in Vietnam based on the Geodetic Boundary Value Problem approach

SUMMARY In the realisation of International Height Reference System, determination geopotential value and its variations in time plays an important role. this study, geodetic boundary problem approach is applied for direct gravity potential using a GOCE global field model enhanced with terrestrial data. This carried out on Global Navigation Satellite System-Continuously Operating Stations (GNSS-CORS) stations towards System Vietnam. First, effects omission error, indirect bias term disturbing systematic cumulative errors levelling data are estimated. These affect estimated value. The results calculated GNSS/levelling points show that effect DIR-R5 (up to degree/order 260) error offset quite significant. was eliminated high-resolution remove-compute-restore technique. can be safely neglected by degrees higher than 60 study region. modelled removed third-order polynomial model. Then, mean zero-height Vietnam local vertical datum equal ${\rm{W}}_0^{{\rm{LVD}}}$ = 62 636 846.69 m2 s–2 standard deviation 0.70 based proposed approach. Finally, used determine surface three GNSS-CORS Based time-series component derived from GNSS observations as well InSAR data, temporal also these permanent stations. purpose monitor deformation datum. indicate needs monitored determined time-dependent Vietnamese may contribute increase density reference Terrestrial Frame, which being researched implemented Association Geodesy.