The Ethiopian gravimetric geoid: ETH-GM21

The ETH-GM21 model is a gravimetric geoid of 2'x2' spatial resolution developed over Ethiopia. This model has been computed using terrestrial and airborne gravity data together with the EIGEN-6C4 GGM and the SRTM3 digital elevation model. The ETH-GM21 model has been determined by using the remove-compute-restore procedure and the least-squares collocation method, obtaining geoid undulations referred to WGS84. With the use of geometric geoid heights obtained from 46 GNSS/levelling data distributed over Ethiopia, the accuracy of the ETH-GM21 gravimetric geoid model has been estimated to ±13 cm. The geoid model is provided in ISG format 2.0 (ISG Format Specifications), while the file in its original data format is available at the model ISG webpage.