###### Xu Peiliang and Reiner Rummel

**Publications on Geodesy 34, Delft, 1991. 51 pagina's. **** ISBN-13: 978 90 6132 240 5. ISBN-10: 90 6132 240 5.**

## Abstract

Vertical datum connection is investigated from the view point of quality, i. e. accuracy, reliability and detectability, based on the method originally proposed by Rummel and Teunissen (1988). Three simulations are carried out. The levelling accuracy is assumed to be 1 mm/km and the position accuracy of space stations 5 cm. The three error models of the geoid used are the Rapp-81 model, a tailored gravitational field and the GEM-T1-related variance-covariance matrix. The results show that the quality of the vertical datum connection depends on the relative accuracy of levelling and space stations, but in particular on that of the geoid. It is also related to the number of space stations inside each datum zone and their geographical distribution. Only when the absolute determination of vertical datum is required, the absolute accuracy of the space stations plays an important role. Finally, we discuss an alternative datum connection model using terrestrial gravity anomalies and satellite derived geopotential coefficients.

## Contents

- Abstract 3
- Acknowledgements 3
- Introduction 4
- Mathematical model for the vertical datum connection 7
- Prior precision matrices of geometric and normal heights 21
- The geoidal heights and their accuracy 25
- Simulation Results 31
- An alternative datum connection model using terrestrial gravity anomalies and satellite geopotential coefficients 45
- Conclusions 47
- References 49