ETH–GM21: A new gravimetric geoid model of Ethiopia developed using the least-squares collocation method

Ephrem Y. Belay, Walyeldeen Godah, Malgorzata Szelachowska, Robert Tenzer

Research output: Journal article publicationJournal articleAcademic researchpeer-review

3 Citations (Scopus)


The determination of an accurate national geoid model remains one of the main challenges of geodetic research projects in Ethiopia. The main aim of this study is to develop a new gravimetric geoid model, named the ETH–GM21, over Ethiopia. This new geoid model is based on a combination of terrestrial and airborne gravity data together with the state-of-the art combined Global Geopotential Model (GGM) and the high-resolution SRTM3 (Shuttle Radar Topography Mission with a spatial resolution of 3 arc-second) global digital elevation model. The ETH–GM21 has been determined using the remove-compute-restore (RCR) procedure and the least–squares collocation method. The accuracy of ETH–GM21 gravimetric geoid model has been evaluated using geometric geoid heights obtained from GNSS (Global Navigation Satellite Systems) and levelling data distributed over the country. On the basis of this evaluation the estimated accuracy of geoid heights from the ETH–GM21 geoid model is at the level of 13 cm. The ETH–GM21 can be recommended as a first relatively accurate vertical reference surface for a definition of heights within the whole Ethiopia.

Original languageEnglish
Article number104313
JournalJournal of African Earth Sciences
Publication statusPublished - Nov 2021


  • Geoid
  • GGMs
  • GNSS/levelling
  • Least–squares collocation
  • Terrestrial and airborne gravity data

ASJC Scopus subject areas

  • Geology
  • Earth-Surface Processes


Dive into the research topics of 'ETH–GM21: A new gravimetric geoid model of Ethiopia developed using the least-squares collocation method'. Together they form a unique fingerprint.

Cite this