A hybrid method to determine a local geoid model—Case study

摘要

This paper studies the methodology to construct an accurate local/regional geoid model. To achieve the objective an integration of all the information/data available must be performed. A hybrid approach of so-called sequential processing is employed in this study. It involves three steps: the construction of a gravimetric geoid using the well-known remove-restore technique; the least squares fitting of 3-parameter transformation to remove the bias and tilts between the gravimetric geoid and GPS/leveling data; further refinement of the geoid model with GPS/leveling data and other information. The study is focused on the last step of signal extraction. The proposed approach was used in the determination of the Hong Kong geoid model and the Shenzhen geoid model. Their accuracy was evaluated with independent GPS/leveling data. These case studies indicate that the absolute accuracy of a centimeter and relative accuracy of some 1 part per million (ppm) of a local geoid model are achievable if the methodology is carefully designed and all the information/data are fully utilized.