The ColWRRT-Minia2019 gravimetric geoid model has been computed by the Civil Engineering Department of Minia University. It has been worked out in the frame of the International Association of Geodesy Joint Working Group 2.2.2 "The 1 cm geoid experiment" and the so called "Colorado experiment". The area covered by the models is 110°W ≤ longitude ≤ 102°W, 35°N ≤ latitude ≤ 40°N with a grid spacing of 1' in both latitude and in longitude. The computation is performed by the Window Remove-Restore Technique (WRRT), subtracting the effect of the topographic-isostatic masses of the data window from the reference model to obtain an adapted reference model to be used in the traditional remove-compute-restore procedure. The chosen reference model is xGEOID17RefB, complete to degree and order 2190. The window-reduced gravity anomalies are used to compute the geoid undulations by employing Stokes formula with Meissl modified kernel (with a cap size of 0.5°). The window restore step yields the final geoid. The accuracy of the ColWRRT-Minia2019 model, when compared against GSVS17 GPS/leveling, is equal to 3.0 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.

The International Service for the Geoid (ISG) was founded in 1992 (as International Geoid Service - IGeS) and it is now an official service of the International Association of Geodesy (IAG), under the umbrella of the International Gravity Field Service (IGFS). The main activities of ISG consist in collecting, analysing and redistributing local and regional geoid models, as well as organizing international schools on the geoid determination (Reguzzoni et al., 2021).