Unification of national surveying vertical datum
(1.School of Telecommunication, Dalian University of Technology, Dalian 116024, China2.Department of Ocean Surveying, Dalian Naval Academy, Dalian 116018, China)
Abstract: The vertical datum of China is composed of leveling datum for heights and chart datum for depths. The determination of national leveling datum and its disadvantages were discussed firstly. The local mean sea level and chart datum with its guarantee rate of navigation safety were studied secondly. The models of unification of national surveying vertical datum, such as optimization model of mean sea level, adoption of New Chinese quasi-geoid of 2000(CQG2000) and time-invariant global geoid were suggested finally.
Key words: vertical datum； leveling datum； chart datum； geoid； quasi-geoid