Rigorous Calibration of a Spring Gravimeter for Accurate Earth Tide Parameters at San Juan (Argentina)

Abstract

In the Province of San Juan, Argentina, high precision geodetic instruments are operated whose observations must be corrected to compensate for the effects of the Earth's tides. Currently, this can be done using the parameters predicted either by theoretical models or local parameters determined by in situ observations. This work reports the results of the analysis of San Juan's tide records acquired with a spring vertical gravimeter (Scintrex CG5). The success of the use of spring relative gravity data in tidal analysis depends on accurate calibration and the proper removal of the instrumental drift from the gravimeter. The instrumental drift of the different registry segments was modeled by polynomial functions. The amplitude calibration factor of the gravimeter was determined by simultaneous gravity measurements with an SG038 superconductor gravimeter, then analyzed in the time and frequency domains. The tidal parameters of the harmonics K1 and M2 derived from tidal analysis are consistent (better than ± 0.05%) with the theoretical parameters for different models of the Earth's interior. The difference between the tested ocean tide models is negligible.