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Very Long Baseline Interferometry (VLBI) serves as one of the common geodetic methods to define the global reference frames and monitor Earth's orientation variations. The technical upgrade of the VLBI method known as the VLBI Global Observing System (VGOS) includes a critical re-design of the observed frequencies from the dual band mode (S and X band, i.e. 2 GHz and 8 GHz) to observations in a broadband (2 – 14 GHz). Since 2019 the first VGOS experiments are available for the geodetic analysis in free access at the International VLBI service for Geodesy and Astrometry (IVS). Also regional-only subnetworks such as European VLBI stations have succeeded already in VGOS mode. Based on these brand-new observations we review the current geodetic data analysis workflow to build a bridge between geodetic observed delays derived from different bands.

Precise measurements of the Earth’s shape, gravity field, and rotation provide critical data for many geoscientific disciplines. In order to obtain reliable data, an accurate, stable, and global reference frame is required. The International Terrestrial Reference Frame, where station positions are modeled linearly, is commonly used throughout the geoscientific community for this purpose. Mass redistribution in the geophysical fluids, namely atmosphere, oceanic, and continental hydrology, cause time dependent variations in station coordinates, and other parameters such as the geocenter coordinates. Tidally-induced loading is described in the IERS Conventions. Models for non-tidal loading are available through the Global Geophysical Fluid Center. An overview of these models is given and comparisons were carried out. Within these comparisons, the best agreement was observed between the two atmospheric models, whereas the biggest discrepancies were found between the hydrology models. The processing setup for the Very Long Baseline Interferometry (VLBI), Satellite Laser Ranging (SLR) and Global Navigation Satellite Systems (GNSS) solutions is described, with loading displacement values introduced at the observation level. By using of non-tidal loading models the RMS of the height is reduced for 93% of the GNSS stations, with a max. reduction of 50%. The model impact on the station height in Wettzell derived by GNSS, SLR and VLBI shows a good agreement. In SLR results the Blue-Sky effect is visible. Applying the loading models reduced the seasonal variations visible in the geocenter time series derived by SLR almost completely.