GEOID QUASI-GEOID Separation Computation Using the Grace And GOCE Global Geopotential Model in Semien Mountains, Ethiopia
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Date
2023-08
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Addis Ababa University
Abstract
Different reference systems are used to determine height,which are quasi-geoids and geoids. The definition of the geoid and telluroid (or, more generally, the quasi-geoid) is connected to these height systems. The optimal technique for computing orthometric heights has been a topic of discussion for more than a century. In mountainous regions, it is challenging to determine geoid and quasi-geoid features using GPS technology. The highest point of a mountain in Ethiopia's highlands is known as Ras Dashen. To tackle boundary issues for mountainous places such as the Ethiopian Semein plateau, a satellite data model is required to ascertain the distinction between geoid and quasi-geoid. We have written this research article to support this investigation. For individuals working in this field, determining the distance between the two references is quite helpful. Calculating the distance between them is important to transform what we receive from one to another.Although there are other ways to determine this gap, we employed satellite earth models created using satellite data for this work. There are three different kinds of models: models created only using GRACE satellite data, models created only using GOCE satellite data, and models created using both GRACE and GOCE data. Our search for the model reference height type was based on E Topo. As a result, Sjoberg's exact formula was used to calculate it in this study using the geoid-quasi-geoid separation model. Using the ETOPO 1 and TC programs from the GRAVSOFT package, the gravity anomaly in the case area was determined. This study investigated variations in the results of the order factor in the application of gravity in addition to the type of data. Models from the International Center for Global Earth Models, including SGG-UGM-2, IGGT_R1C, GO_CONS_GCF_2_TIM_R6, and ITSG-Grace2018, were used in this determination of Geoid-Qusigeoid separation.With the help of these models, we searched for various gravitational field functions, but primarily we searched for the separation between the geoid and quasi-geoid separation in all four models, and we discovered that the minimum and maximum results are, respectively, 0.388, 0.356, 0.365, 0.360 and 4.730,3.798,3.755,and 3.760 meter.