Experimental results on the tidal resonance effect of the liquid core

Abstract

Molodenskii's theory on the resonance effect of the liquid core predicts anomalous amplitudes in the diurnal spectrum for earth tide registrations of gravity and tilt. A two years recording of an Askania gravimeter at Kiel University has been analysed using three different numerical methods: harmonic analysis (least squares method), gliding harmonic analysis, and Fourier spectral analysis. Because of difficulties in resolving tidal waves near the resonance frequency, efforts were made towards improving the Fourier spectral analysis by successive subtraction of high amplitudes in the Fourier spectrum. The resonance of the liquid core has been observed with a high degree of confidence thereby supporting Molodenskii's model calculations.