Abstract
AbstractThe Earth’s crust experiences deformation caused by a range of geophysical phenomena, including the motion of tectonic plates and the redistribution of surface fluids like the atmosphere, oceans, and continental water. These natural processes result in substantial changes in the Earth’s crust load, leading to the displacement of geodetic sites and alterations in station coordinates over time scales that can vary from yearly to sub-diurnal periods. Geophysical models are employed in Very Long Baseline Interferometry (VLBI) analysis to consider loading effects resulting from the global movement of the geophysical fluids to accurately estimate parameters of interest. Given VLBI’s significance as a key technique for terrestrial reference frame determination, the accuracy of geophysical models becomes paramount. This study focuses on comparing elastic surface loading products, specifically on the corresponding changes in station coordinates. Non-tidal surface loading (NTSL) data is obtained from different loading services, such as VieAPL, EOST, IMLS, and ESMGFZ. Notably, VieAPL exclusively provides non-tidal atmospheric loading (NTAL), while EOST, IMLS, and ESMGFZ provide all three NTSL components—NTAL, non-tidal oceanic loading, and hydrological loading. The analysis of 20 years data of NTSL (from 2001 to 2020), extracted from these services demonstrates consistency among them, except for the hydrological loading component of ESMGFZ. The implementation of NTSL models in VLBI analysis has revealed that baseline length repeatability shows improvements or remains stable in 90.25% of the baselines for IMLS, 89.02% for EOST, and 86.18% for ESMGFZ. Additionally, the application of NTSL models leads to an improvement in the standard deviation of station height by 65% in both EOST and IMLS, and by 61.25% in the case of ESMGFZ. We also investigate the variance reduction coefficients, demonstrating the distinctions in loading corrections offered by various services.
Publisher
Springer Berlin Heidelberg