A Geodetic Determination of the Gravitational Potential Difference Toward a 100-km-Scale Clock Frequency Comparison in a Plate Subduction Zone

Abstract Recent advances in the developments of optical atomic clocks have enabled 10 −18 -level frequency comparisons between fibre-linked clocks. Therefore, chronometric leveling with an uncertainty on order 1 cm has become possible, based general theory relativity. Since measurement does not deteriorate increasing fibre length, applications geodesy, particularly unification height reference systems, been actively studied. In Japan, a comparison is under experimentation using link connecting two lattice approximately 100 km apart. This study estimates both potential difference these clock sites geodetic method and its to verify results leveling, which will be obtained near future. We use orthometric heights derived from surveys repeated for monitoring crustal deformation. When discussing at 1-cm level height, effects temporal variations gravitational need considered due various geophysical phenomena, including tides. Our show that measurements by largest tidal changes during can cause systematic errors few mm. The nontidal ocean bottom pressure atmospheric are more than magnitude smaller this spatial scale. An upper limit groundwater also estimated. future −19 , must rigorously evaluated.