Abstract.
A variety of mathematical models exist with which to combine long-wavelength geoid information from an Earth gravity model (EGM) with terrestrial gravity data. As new data become available, such as an extended or refined EGM and/or some variance–covariance information from terrestrial gravity data, this new information can be combined with a previous geoid model through a so-called hybrid estimator. The hybrid estimator is defined as a two-step estimator, which provides a solution that is a compromise between computational labour and matching of the entire data set. Some commonly used geoid modifications are compared, and several hybrid estimators are introduced. It is concluded that, in general, hybrid estimators linking the new information to old data by the least squares principle should be preferred to deterministic combinations.
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Acknowledgements This paper was written whilst the first author was a visiting scientist at Curtin University of Technology in Perth, Western Australia. The hospitality of Professor Will Featherstone and his colleagues in the Western Australian Centre for Geodesy is cordially acknowledged. This research is financially supported by Australian Research Council grants A3094030 and DP0211827. Finally, the authors would like to thank the three reviewers and editor for their time and effort in providing constructive comments on an earlier version of this manuscript.
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Sjöberg, L., Featherstone, W. Two-step procedures for hybrid geoid modelling. Journal of Geodesy 78, 66–75 (2004). https://doi.org/10.1007/s00190-003-0367-9
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DOI: https://doi.org/10.1007/s00190-003-0367-9