Gravity reference at the Argentinean–German Geodetic Observatory (AGGO) by co-location of superconducting and absolute gravity measurements

Ezequiel D Antokoletz,Hartmut Wziontek,Claudia N Tocho,Reinhard Falk

doi:10.1007/s00190-020-01402-7

Abstract

The Argentinean–German Geodetic Observatory (AGGO) is a fundamental geodetic observatory located close to the city of La Plata, Argentina. Two high-precision gravity meters are installed at AGGO: the superconducting gravimeter SG038, which is in operation since December 2015, and the absolute gravimeter FG5-227, which has provided absolute gravity measurements since January 2018. By co-location of gravity observations from both meters between January 2018 and March 2019, calibration factor and instrumental drift of the SG038 were determined. The calibration factor of the SG038 was estimated by different strategies: from tidal models, dedicated absolute gravity measurements over several days and a joint approach (including the determination of the instrumental drift) using all available absolute gravity data. The final calibration factor differs from the determination at the previous station, the transportable integrated geodetic observatory, in Concepcion, Chile, by only 0.7‰, which does not imply a significant change. From the combined approach also the mean absolute level of the SG was determined, allowing to predict absolute gravity values from the SG at any time based on a repeatability of 12nm/s2\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$12\\,\\hbox {nm}/\\hbox {s}^{2}$$\\end{document} for the FG5-227 at AGGO. Such a continuous gravity reference function provides the basis for a comparison site for absolute gravimeters in the frame of the international gravity reference frame for South America and the Caribbean. However, it requires the assessment of the total error budget of the FG5-227, including the link to the international comparisons, which will be subject of future efforts.

Highlights

The Argentinean–German Geodetic Observatory (AGGO) is a fundamental geodetic observatory located close to the city of La Plata, Argentina, where all major geodetic tech-Calibration factor and instrumental drift of the SG038 were previously determined at station Transportable Integrated Geodetic Observatory (TIGO)
The calibration factor had to be checked after the installation at AGGO
By including the drops of all absolute gravimeter (AG) observation epochs from January 2018 to March 2019, the SG038 instrumental drift was determined with 110 nm/s2/year from Eq (1), with an estimated uncertainty of 4 nm/s2/year

Summary

Introduction

The Argentinean–German Geodetic Observatory (AGGO) is a fundamental geodetic observatory located close to the city of La Plata, Argentina, where all major geodetic tech-. Calibration factor and instrumental drift of the SG038 were previously determined at station TIGO. The calibration factor was found to be − 736.5 nm/s2/V with an estimated uncertainty of 0.8 nm/s2/V from 3 years of combination with absolute gravity observations. The SG instrumental drift was estimated with 51.9 nm/s2/year, with an estimated uncertainty of 0.3 nm/s2/year, by combining more than 130 AG observation epochs (Wziontek et al 2016). The instrumental drift had to be determined after the new setup since a change in its behavior is normally expected after changes of the magnetic field when re-centering the sphere

Methods

Results

Conclusion