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Accuracy assessment of high and ultra high-resolution combined GGMs, and recent satellite-only GGMs - Case studies of Poland and Ethiopia

Godah Walyeldeen, Szelachowska Małgorzata, Gedamu Andenet A.

Reports on Geodesy and Geoinformatics

2024

Vol. 117

38--44

The launch of dedicated satellite gravity missions (CHAMP, GRACE, GOCE, and GRACE-FO), as well as the availability of gravity data from satellite altimetry and terrestrial/airborne gravity measurements have led to a growing number of Global Geopotential Models (GGMs) developed. Thus, the evaluation of GGMs is necessary to ensure their accuracy in recovering the Earth's gravity field on local, regional, and global scales. The main objective of this research is to assess the accuracy of recent GGMs over Poland in Central Europe and Ethiopia in East Africa. Combined GGMs of high (degree and order (d/o) 2190) and ultra high-resolution (d/o 5540) as well as five satellite-only GGMs were evaluated using gravity data from absolute gravity measurements and airborne gravity surveys over Poland and Ethiopia, respectively. Based on this evaluation, the estimated accuracy of the high-resolution combined GGM is at the level of 2 mGal. The estimated accuracy for the ultra-high-resolution combined GGM is ~2.5 times lower. The satellite-only GGMs investigated recover the gravity signal at an accuracy level of 10 mGal and 26 mGal, for the areas of Poland and Ethiopia, respectively. When compensating for the omitted gravity signal using a high-resolution combined GGM and the topography model, an accuracy of 2 mGal can be achieved.

Dependences in the pillar 'Earth's gravity field' of GGOS - description using UML notation

Paśnicka M., Szafranek K., Zwirowicz-Rutkowska A.

Reports on Geodesy

2012

z. 1/92

135--142

Earth’s gravity field is one of three pillars of the Global Geodetic Observing System (GGOS). Gravity measurements are made using both classical methods by the means of ground measurement facilities (relative and absolute gravimetry) and methods based on the satellite techniques (SLR, missions CHAMP, GRACE, GOCE) or airborne gravimetry. The main objective of this GGOS pillar is to determine geoid’s shape, Earth’s static gravitational potential and temporal variations induced by solid Earth processes and mass transport in the global water cycle. The paper presents relationships between the main classes of diagrams of the Earth’s gravity field described using UML (Unified Modelling Language). Such description can be helpful in the analysis of the gravitational field pillar linkages with other pillars of GGOS. The main purpose of this paper is to give the full explanation of connections between all Earth’s gravity field GGOS components. Key words: Earth’s gravity field, UML, GGOS.