Determination of the gravimetric factor at the Chandler period from Earth orientation data and superconducting gravimetry observations

Abstract

Summary We have used more than 8 years’ worth of a combination of superconducting gravimeter (SG) data from the Strasbourg station and Very Long Baseline Interferometry (VLBI) Earth orientation data in order to determine the gravimetric factor at the Chandler period of 435 days. The method presented here takes advantage of the relation between the rotational potential and the gravity variation at the Earth’s surface. The length of the data set is a critical parameter in such a determination but appears to be long enough to separate the annual and Chandler components. Our results are in a good agreement with the long-period theoretical gravimetric factor relative to an elastic solid earth model and a static pole tide in the oceans. We also find that the effect of the atmosphere (computed from a global atmospheric model assuming a static response of the oceans to air-pressure changes) is not negligible and perturbs the amplitude of the Chandler wave observed in the gravimetric data.