Določitev geoida v severozahodni Tuniziji z metodo remove-compute-restore (RCR)

Geoid modelling in Northwestern Tunisia using the Remove – Compute – Restore (RCR) method

Author(s):

Ali Chaieb, Nahla Gam, Mourad Salhi

Abstract:

This study presents the development and evaluation of a local gravimetric geoid model for Northwest Tunisia. The model was constructed using the Remove-Compute-Restore (RCR) method, integrating terrestrial gravity measurements, GPS-survey data, digital elevation models, and the global geopotential model EGM2008. A comprehensive accuracy assessment was first conducted. Among the tested global models (EGM96, EGM2008, EIGEN-6C4), EGM2008 demonstrated superior performance, yielding the smallest standard deviation. The SRTM digital elevation model was identified as the most accurate topographic dataset for the region. The computational workflow involved the calculation of free-air anomalies, residual terrain corrections, and residual gravity anomalies. Stokes' integration was then applied to convert the residual gravity field into residual height anomalies. The final quasi-geoid was restored by combining the EGM2008-derived long-wavelength component, the residual terrain effect, and the gravimetrically determined residual signal. The model was subsequently adjusted using an independent set of GPS-levelled benchmarks to ensure consistency with the national vertical datum. The resulting local geoid model provides a precise and reliable reference surface for converting GNSS-derived ellipsoidal heights into orthometric heights within the study area.

Keywords:

Geoid Modelling, Remove-Compute-Restore, EGM2008, GPS-Levelling, Gravimetry

DOI: 10.15292/geodetski-vestnik.2026.03.391-405

Citation:

Ali Chaieb, Nahla Gam, Mourad Salhi (2026). Določitev geoida v severozahodni Tuniziji z metodo remove-compute-restore (RCR). | Geoid modelling in Northwestern Tunisia using the Remove – Compute – Restore (RCR) method. Geodetski vestnik, 70 (3), 391-405. DOI: 10.15292/geodetski-vestnik.2026.03.391-405