The precise determination of physical heights remains a major challenge in geodesy. Advances in optical clocks offer new opportunities to determine height differences by utilizing relativistic effects. Specifically, the gravitational redshift effect can be used to calculate height differences between distant locations.

The research project "TIME" (Clock Metrology: A Novel Approach to TIME in Geodesy) explores how physical heights can be determined using time transfer instead of traditional frequency comparisons. An optical time transfer link is simulated between the geodetic observatories in Wettzell and Potsdam via the Atomic Clock Ensemble in Space (ACES). Additionally, a fiber-optic connection to the Physikalisch-Technische Bundesanstalt (PTB) in Braunschweig is considered, enabling the use of microwave and laser links. To further expand the network, connections to Grasse, France, and Borówiec, Poland, are also included in the simulation. The project aims to simulate height differences with an accuracy of 20 cm or better over extended integration times.

Currently, the focus is on the analysis of time intervals, particularly those of a few days. These shorter time periods present a particular challenge in terms of modeling and correcting clock and link errors. The impact of these errors is evaluated through various simulations. Additionally, the advantages of common view and non-common view methods for height determination in relation to these integration times are investigated.

We acknowledge the support of the German Research Foundation (DFG) – Project-ID 490990195 – FOR 5456.