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Abstract

The current progress of optical clocks has reached a fractional frequency uncertainty of 1.0x10^-18 which corresponds to a geopotential difference of 0.1 m²/s². Those gravitational potential differences can be observed as gravitational redshift when comparing the frequencies of optical clocks. Even temporal potential variations might be determined with precise optical clocks on low-orbiting satellites, e.g., at altitudes of SLR-like (e.g. LAGEOS-1/2), GRACE-like and GOCE-like missions.In this simulation study, the potential of space-borne precise novel optical clocks for the determination of temporal variations of low-degree gravity field spherical harmonic coefficients will be discussed. We will demonstrate that optical clocks at current achievable level of uncertainty are able to reveal long-wavelength seasonal and secular gravity changes. Different configurations of satellite orbits, i.e. at different altitudes (between 250 and 6000 km) and inclinations, are selected as well as certain assumptions on the clock performance are made. We will quantify how well degree-2 coefficients can be estimated from those optical clock measurements and how it compares to results from SLR data. Keywords: Optical clock measurements in space, temporal long-wavelength Earth’s gravity field variations, Relativistic Geodesy Acknowledgements: This research was funded by the German Research Foundation (DFG) under Germany’s Excellence Strategy EXC 2123 QuantumFrontiers (Project-ID 390837967) and the Collaborative Research Centre CRC-1464 “TerraQ - Relativistic and Quantum-based Geodesy”.