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GR: Fachverband Gravitation und Relativitätstheorie
GR 3: Rel. Geodesy
GR 3.2: Vortrag
Dienstag, 1. April 2025, 14:35–14:55, ZHG007
Chronometry in spacetime: a clock-based global height system — •Dennis Philipp1,2, Asha Vincent3, Christian Lisdat4, and Juergen Mueller3 — 1ZARM, University of Bremen, Germany — 2Faculty of Physics, University of Bremen, Germany — 3Institute for Geodesy, Leibniz University Hannover, Germany — 4Physikalisch-Technische Bundesanstalt, Braunschweig, Germany
Ongoing efforts aim at achieving a globally uniform and consistent International Height Reference System as a global standard for accurately determining physical (height-)coordinates across the world. Near the Earth’s surface, two stationary standard clocks that are separated by 1 cm in height have a redshift of about 10−18 according to Einstein’s theory of General Relativity (GR).
We present a definition of clock observables and chronometry in GR, leading towards a relativistic definition of i) a gravity potential, ii) a notion of chronometric height, and iii) generalized geopotential numbers. Clock comparison in this framework allows for accurate height determination in high-performance clock networks, in which frequency differences can be observed between clock sites and corresponding gravity potential differences can be derived. Height values can be represented by geopotential numbers and measured potential differences between clock locations in a dedicated clock network can be used to estimate the transformation parameters between regional reference frames to resolve distortions. A simulation study is presented that focusses on height systems in Europe and South America to demonstrate the potential impact and benefit of clock-based height systems.
Keywords: Chronometry; Relativistic Geodesy; Clocks; Height; Reference Systems