INTERGEO Agenda - english

The current determination of global Terrestrial Reference Frames (TRFs) is carried out through a combination of space geodetic techniques by using local ties at co-location sites. As part of the DFG research unit Clock Metrology, this project is developing new, innovative strategies for combining space geodetic techniques by introducing a common target (CT) and a common clock (CC) at the geodetic observatory Wettzell (GOW). These serve as a reference point and a common time frame for all techniques at GOW, respectively. The aim is to demonstrate how a CT and CC can contribute to achieve the Global Geodetic Observing System (GGOS) goals of 1 mm accuracy and 1 mm/decade long-term stability for the TRFs. Based on current state-of-the-art standards and models, extensive simulations of observing networks for the Global Positioning System (GPS), Satellite Laser Ranging (SLR) and Very Long Baseline Interferometry (VLBI) have been performed to investigate the impact of the CT and CC on the TRF. Furthermore, extensive software modifications are carried out to introduce the CC into GPS processing, including a new clock parameterization to align GPS clock estimation with VLBI. This study presents the results of introducing the CC in to intra- and inter-technique combinations, including the impact on TRF determination in terms of estimated station coordinates, velocities, and Earth Orientation Parameters (EOPs), and cross-parameter correlations.