Prediction of potential errors of height anomalies of global geoid models for different tidal systems
Authors:   Lviv Polytechnic National University, FEDORCHUK A. 
Published: April 2024

The article presents the method of predicting the errors of height anomalies obtained from high-order global geoid models (EGM_2008, EIGEN_6C4, GECO, XGM2019e2159, SGG_UGM_2) and taking into account different tide systems (free/zero/mean-tide). A correct understanding of how much the choice of the global model height tide system affects the accuracy of calculating the normal heights of the Earth’s physical surface is an important component for obtaining reliable results. The purpose of the work is to predict the potential errors of height anomalies for three main concepts of tidal corrections (tidal systems) used in the creation of global geoid models. Method. The essence of the prediction method is to find a connection between the height anomalies of the global geoid models and the PL-quasi-geoid2021 regional quasi-geoid model. On the basis of the established connection, the prediction of potential errors of height anomalies was made, taking into account the choice of one or another system of tides. The prediction of the errors of height anomalies is implemented on the basis of 200 GNSS stations located on the territory of Ukraine and in the border sector. To find the connection between the heights of the global geoid models and the PL-quasi-geoid2021 regional model, a territory was allocated in the western border sector measuring 48°-52° in latitude and 21°-25° in longitude. For 36 GNSS stations located in the border area, a scale coefficient between global and regional height anomalies was found. Results. In the border sector, the factual errors of height anomalies are estimated at the level of 0.01-0.03 m based on the standard deviation and at the level of the mean square deviation of 0.17–0.18 m, 0.15-0.16 m, and 0.08–0.09 m for the free, zero and mean-tide systems, respectively. The standard deviations of the predicted potential errors for the border sector were 0.02-0.03 m, and the mean square values were 0.17–0.18 m, 0.13 m and 0.06 m for similar tidal systems. The residual errors of height anomalies for the border sector amounted to 0.03 m according to the standard and mean square deviation. Assessment of accuracy prediction of potential errors of height anomalies of models EGM_2008, EIGEN_6C4, GECO, XGM2019e2159, SGG_UGM_2 carried out on the basis of 200 GNSS stations was 0.03 m by standard deviation and 0.15 m (free-tide), 0.13 m (zero-tide) and 0.06 m (mean-tide) by mean square value. Scientific novelty. First implemented was the prediction of potential errors of height anomalies of global geoid models, which was performed by the scale factor for GNSS stations located on the territory of Ukraine and taking into account different tidal systems. Practical significance. The predicted errors of height anomalies make it possible to calculate the normal heights of GNSS stations and points on the Earth’s physical surface with an accuracy of about 3 cm. The obtained results allow the use of height anomalies of global geoid models of high order for more accurate geodetics work.