Local quasigeoid modeling at Argentinean stations of the International Height Reference Frame (IHRF)

Abstract

In the year 2015, the International Association of Geodesy (IAG) introduced the International Height Reference System (IHRS) as the global standard for the determination of physical heights. Its realization, the International Height Reference Frame (IHRF), relies on the computation of vertical coordinates (geopotential numbers) at selected stations, which can be achieved through precise local or regional gravity field modeling. This study focuses on recovering geopotential numbers referred to the IHRF at the Argentinean core reference stations from high-precision, pure gravimetric local quasigeoid models computed in the surroundings of each station. The remove-compute-restore scheme was employed, using the XGM2019e Global Geopotential Model (GGM) and the Residual Terrain Modeling (RTM) approach for computing long and short-wavelength gravity effects, respectively. Residual height anomalies were estimated with two independent methods: Least-Squares Collocation (LSC) and one-dimensional Fast Fourier Transform (1D-FFT). Local models were validated against GNSS/leveling data. The models outperform XGM2019e by up to 50%. Their precision ranges from 0.061 m in flat areas with high-quality gravity and GNSS/leveling data to 0.170 m in areas with complex topography. IHRF geopotential numbers were finally recovered from the pure gravimetric 1D-FFT models, following the guidelines of the IHRF Coordination Center (IHRF CC). The results of this study will be proposed for the next realization of the IHRF. Furthermore, data processing strategies, as well as the parameters obtained for each of the models, will serve as a basis for the future development of a new Argentinean quasigeoid model.