[G04-2] Earth rotation and geodynamics II

[G04-2-04] Excitation study of the observed Chandler wobble based on GRACE and SLR gravity data

^○Aleksander Brzezinski^{1, 2}, Jolanta Nastula² (1.Warsaw University of Technology, Department of Geodesy and Cartography, Warsaw, Poland, 2.Space Research Centre of the Polish Academy of Sciences, Warsaw, Poland)

We investigate the excitation of the free Chandler wobble by the large-scale processes taking place in the external fluid layers including the atmosphere, the oceans and the land hydrology. The mass term of excitation is expressed by the so-called gravimetric excitation function estimated from time variation of degree-2, order-1 harmonics of the Earth gravity field, derived from Gravity Recovery and Climate Experiment (GRACE) and the Satellite Laser Ranging (SLR) data. Our first results (Brzezinski and Nastula, presented at GAGER2016 Symposium in Wuhan) indicated that the Chandler wobble observed during 2003–2014 can be fully explained by the GRACE-derived mass term of excitation. Here we extend that study by considering alternative GRACE data sets which are publicly available, like the CNES/GRGS and Tongji solutions. In addition, we include also in the analysis the motion term of excitation taken from different geophysical models.