Abstract:
This scientific article describes the research results of a state - level project “Estimative research of standard surfaces of the sea level (“zero” depth surface, mean and highest sea surfaces) by the methods of geodesy, oceanography and modern tectonics serving the work construction and planning the coast of Vietnam in trend of climate changes” with code KC09.19/11-15 related to the construction of local mean dynamic topography (local Mean Dynamic Topography of Vietnam - MDTVN) best fit to mean sea surface on the territorial waters of Vietnam. MDTVN model will be used as geographical base map on the East sea for making thematic maps of different types and measuring - making topographical maps of the sea bottom. MDTVN model is constructed based on local geoid best fit to the mean sea surface at the tide gauge station Hon Dau to determine the height of any points on the mean sea surface in the state height system HP72.
Data used for the construction of the MDTVN consist of the DTU10 MDT model of the Technical University of Denmark,geopotential W0= 62636847.2911 m2.s-2 of the Hon Dau local geoid and local mean sea surfaces determined from sea level measurement data (till June 2014) at the tide gauge stations Co To, Hon Dau, Hon Ngu, Tien Sa (Da Nang), Quy Nhon, Vung Tau, Con Dao and Phu Quoc. The DTU10MDT model has been used due to its coverage on the world oceans in general and on the territorial waters of Vietnam in particular.
An analytic process of the global mean sea surface from the DTU10 MDT model has shown that from the paralel of 19057’ to the south of Vietnam, the global mean sea surface has been systematically inaccurate as compared to the local mean sea surfaces at the tide gauge stations. A correction of the global mean sea surface’s systematic error allows to get the MDTVN model with hight accuracy at the level of ± 6.1cm.
Keywords:
GPS, local geoid, MDT (Mean Dynamic Topography), mean sea surface, tide gauge station.