Effect of DHM resolution on gravity reduction and geoid determination: case study for Egypt
20/09/2016 | 17:00 | Session 3: Local/regional geoid determination methods and models
Author(s): Hussein Abd-Elmotaal, Atef Makhloof and Mostafa Ashry
Hussein Abd-Elmotaal, Atef Makhloof and Mostafa Ashry
In the framework of the IAG African Geoid Project, it is needed to estimate the effect of the resolution of the used digital height models (DHM's) on the reduced gravity anomalies and on the computed gravimetric geoid. This paper deals with such a study in Egypt as a prototype test. The available set of DHM's has a finest resolution of 1" × 1" (Abd-Elmotaal et al., 2013). Different combinations of DHM resolutions have been tested. Gravity reduction has been carried out using the window technique (Abd-Elmotaal and Kühtreiber, 2003) in order to get rid of the double consideration of some part of the topographic-isostatic masses. The reduced gravity anomalies have been used to compute gravimetric geoids in each test case employing 1D-FFT technique. The computed geoids have been fitted to the GPS-levelling derived geoid using an optimum geoid fitting technique developed by Abd-Elmotaal and Makhloof (2015). The comparison among the results have been carried out at two levels: the reduced gravity anomalies and the computed geoids. The results are shown and widely discussed.