On the accuracy of (quasi) geoid models relatively UELN/EVRS2000 height systems

Nowadays the Baltic Height System 1977 operates in Ukraine, the starting point of which is the zero of the Kronstadt banchmark. However, the current height system in Ukraine is morally obsolete primarily due to the great distance from the zero-point of height (about 2 thousand km) and the difficulty of adapting to the use of satellite surveying methods. Therefore, today it does not correspond to the level of development of modern geospatial technologies and it needs to be modernized. The most optimal way to modernize the height network of Ukraine is its integration into the United European Leveling Network UELN, the zero point of which is the Amsterdam banchmark. Within the framework of such integration it is necessary to create a high-precision geoid model for the territory of Ukraine, connected to the UELN/EVRS2000 height system. Aim. The purpose of the work is to compare the accuracy of different geoid/quasigeoid models and the global gravitational field of the Earth on the Western Ukraine area (border region) relative to the heights of points in the height system UELN/EVRS2000, where GNSSleveling is performed, and to determine the most optimal model in relation to which a high-precision geoid model can be created, consistent with the UELN/EVRS2000 height system.Method. To obtain the heights of leveling points on the Ukraine area in the UELN/EVRS2000 height system we performed I class leveling on two lines from the fundamental benchmarks on the territory of Ukraine (heights are known in the Baltic height system 1977) to I class benchmarks on the Poland area (UELN/EVRS2000 height system). GNSS-leveling in static mode (1-second sampling observations for more than 6 hours) was performed on all fundamental and ground benchmarks, as well as horizontal marks. Results. The heights of the quasigeoid at 26 points are obtained from the performed measurements. The heights are compared with three global models of the Earth’s gravitational field: EGM2008, EIGEN-6C4 and XGM2019e_2159 (the maximum order of all these models is 2190), as well as with the European geoid EGG2015. It is established that the best accuracy (≈ 7 cm) allows to obtain the European geoid EGG2015. Scientific novelty and practical significance. For the first time the accuracy of the Earth’s gravitational field models and geoid models on the Ukraine area is investigated at points where the height in the UELN/EVRS2000 height system is known. We established that when constructing a high-precision quasigeoid using the “Remove–Restore” procedure, it is best to use the European geoid EGG2015 as a systematic component.