Test of Theoretical Solid Earth and Ocean Gravity Tides

Abstract

S U M M A R YData from three superconducting gravimeters at four different locations are analysed for agreement with theoretical computations of gravity tides and of the influence of ocean tides on gravity. The absolute value of the measured tide is determined by an independent absolute calibration of the gravimeters. The method differs from previous tests of tide theories in that it compares the entire predicted time series rather than specific harmonic constituents. In this way it is possible to test the solid earth and ocean tide effects independently. We find that the ratios of observed to predicted solid earth tides at different locations are the same within an uncertainty of about kO.2 per cent. However, the magnitude of the tides deduced by the absolute calibration of the gravimeters is 0.6 per cent larger than the theoretical solid earth tide. We point out that an accurate determination of the solid earth tide in this way provides a direct comparison between the gravitational constant, G, at laboratory scales and at the distance to the moon.

A First Reliable Gravity Tidal Model for Lake Nasser Region (Egypt)

“…We follow a theoretical approach for determination of the scaling (calibration) factor based on theoretical Earth tides as reference (Figs. 2d-f, 3d-f) which was first suggested by Goodkind (1996). Other than the theoretical Earth tides, gravity variations due to the atmosphere, hydrosphere, ocean and polar motion, have to be accounted for, because the raw gravity data also include these signals.…”

Superconducting Gravimetry

“…Several authors have argued that tidal analysis of an SG record is a useful calibration tool (e.g., Goodkind, 1996). Of equal importance is the relative stability of the amplitude calibration, and Merriam (1995a,b) had inferred this for the model TT70 at Cantley using the tidal admittances of the M 2 , O 1 , and K 1 waves from 3 years of data.…”