Chronometric geodesy: methods and applications

TL;DR

This paper reviews the principles and recent advances in chronometric geodesy, focusing on relativistic time measurement, clock comparison techniques, and their applications in geoid determination and geodesy.

Contribution

It provides a comprehensive overview of the methods, theory, and applications of chronometric geodesy, including recent European project results and simulation studies.

Findings

Unified relativistic redshift corrections for European clocks

Potential of clock comparisons to improve geoid determination

Uncertainty analysis of geodetic methods

Abstract

In section 2, we introduce fundamental concepts of GR concerning the measurement of time, relativistic reference systems and we review the recent literature of chronometric geodesy. In section 3 we introduce the theory of frequency standard comparisons, beginning with the Einstein equivalence principle, followed by the description of the frequency techniques, and finally, we describe clock syntonization and the realization of timescales. Section 4 describes the geodetic methods for determining the gravity potential, namely the geometric levelling approach and the GNSS/geoid approach, as well as considerations about the uncertainties of these methods. In section 5 we describe the European project ITOC where unified relativistic redshift corrections were determined for several clocks in European national metrology institutes. Finally, in section 6 we present numerical simulations exploring what could be the contribution of clock comparisons for the determination of the geoid.