First Six Months of Superconducting Gravimetry in Argentina

Abstract

On December 16th, 2015, the superconducting gravimeter SG038 started to measure again after it was moved from the previous station in Concepcion, Chile to the Argentine-Germany Geodetic Observatory (AGGO) near the city of La Plata in Argentina. The temporal gravity variations recorded with superconducting gravimeters (SG) enables research in several geodetic and geophysical studies that involve Earth’s changes in the surface gravity field. In particular, it allows computing local models of earth tide parameters. The superconducting gravimeter SG038 at station AGGO was used to monitor gravity for the first 6 months after its installation. The gravity time series was preprocessed after removing the principal constituents of the largest influences of the gravity signal that can be modeled sufficiently accurate like atmospheric effects, theoretical tides of the solid Earth, ocean loading effects and pole tides. In the remaining residual signal spikes were fixed, earthquake perturbations were reduced. Finally, the theoretical tides of the solid Earth and ocean loading effects previously removed were restored to obtain the corrected gravity signal. The transfer function of the SG038 was determined by analyzing the step response of the whole system. Empirical amplitude and phase response functions are presented. The group delay at zero frequency was used in the tidal analysis. By harmonic analysis of the preprocessed hourly data, amplitude factors and phases for tidal wave groups were estimated.