A global combination of geodetic techniques at the observation level: new perspectives on the terrestrial reference frame

We describe the development and assessment of a new terrestrial reference frame (TRF)based on a combination of geodetic techniques at the observation level over the period 2010-2022. Included in the solution are observations from the Global Positioning System (GPS), Satellite Laser Ranging (SLR) and Very Long Baseline Interferometry (VLBI). Though the resulting TRF solution is based on only 12.6 years of data, it is competitive with the international (ITRF2020) standard in terms of fundamental frame parameters (origin and scale) and their temporal evolution, both linear and seasonal. The relative rates of origin (3D) and scale (at Earth's surface) are 0.2 mm/yr and 0.1 mm/yr respectively. Absolute scale (at epoch 2015.0) and 3D origin both differ by 2 mm. In addition to station positions and velocities, our combined solution includes Earth orientation parameters (EOP), low-degree zonal coefficients (J2 and J3) of the geopotential and precise orbit solutions for all participating satellites (GPS, GRACE & GRACE Follow-on tandems, Jason 2 & 3, and LAGEOS 1 & 2).