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Abstract

Work on the implementation of the International Height Reference Frame has been underway for several years. This requires analysis both at the global level as well as at the local level. Unifying vertical datums can be challenging due to various factors, including the abundance of height reference systems, their lack of uniformity, and the absence of elevation in-time change models.This research focuses on the possibility of the unification of the existing Polish reference height frame PL-EVRF2007-NH with the IHRF. We have concentrated on several analyses performed related to: the local alignment of the vertical network in terms of geopotential numbers, the use of terrestrial gravimetric data and global geopotential models of various resolutions in the process of determining the local ΔW₀ value, and testing multiple sets of vertical network points that could be the basis for the unification of these frames.By conducting analyses and numerical tests, recommendations were formulated regarding the methodology of unifying the PL-EVRF2007-NH and IHRF frames in Poland. Specifically, the suggestions include evaluating and selecting the optimal GGM model, choosing reference points for the local height frame, and gathering and evaluating the quality of data related to normal heights or geopotential values.