Acta Geodaetica et Geophysica

, Volume 48, Issue 2, pp 199–208 | Cite as

On the reliability and error calibration of some recent Earth’s gravity models of GOCE with respect to EGM08

  • M. EshaghEmail author


The Gravity field and steady-state Ocean Circulation Explorer (GOCE) mission is dedicated to recover spherical harmonic coefficients of the Earth’s gravity field to degree and order of about 250 using its satellite gradiometric data. Since these data are contaminated with coloured noise, therefore, their inversion will not be straightforward. Unsuccessful modelling of this noise will lead to biases in the harmonic coefficients presented in the Earth’s gravity models (EGMs). In this study, five of the recent EGMs of GOCE such as two direct, two time-wise and one space-wise solution are used to degree and order 240 and their reliability is investigated with respect to EGM08 which is assumed as a reliable EGM. The detected unreliable coefficients and their errors are replaced by the corresponding ones from EGM08 as a combination strategy. A condition adjustment model is organised for each two corresponding coefficients of GOCE EGMs and EGM08; and errors of the GOCE EGMs are calibrated based on a scaling factor, obtained from a posteriori variance factor. When the factor is less than 2.5 it will be multiplied to the error otherwise the error of EGM08 coefficient will be considered as the calibrated one. At the end, a simple geoid estimator is presented which considers the EGMs and their errors and its outcomes are compared with the corresponding geoid heights derived from the Global Positioning System (GPS) and the levelling data (GPS/levelling data), over Fennoscandia. This comparison shows that some of the combined-calibrated GOCE EGMs are closer to the GPS/levelling data than the original ones.


A posteriori variance factor GOCE GPS/levelling EGM08 Degree of resolution Signal and error spectra Geoid Scaling factor 



The author is thankful to the Swedish National Space Board (SNSB) for supporting projects 98/09:1 and 82/11. The Land Survey of Sweden (LMV) and Dr. Jonas Ågren are acknowledged for providing the GPS/levelling data of Sweden, gravity and topographic data of Fennoscandia. Dr. Mette Weber is appreciated for providing the GPS/levelling data of Denmark, Professor Dag Solheim for Norwegian ones and Dr. Veikko Saaranen for those of Finland. Dr-Ing. Christian Gerlach is appreciated for reading and commenting to the draft version of the paper.


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Copyright information

© Akadémiai Kiadó, Budapest, Hungary 2013

Authors and Affiliations

  1. 1.Department of Engineering ScienceUniversity WestTrollhättanSweden
  2. 2.Division of Geodesy and GeoinformaticsRoyal Institute of Technology (KTH)StockholmSweden

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