Acta Geodynamica et Geomaterialia

Title: GEOPHYSICAL EXCITATION OF NUTATION - COMPARASION OF DIFFERENT MODELS
Authors: Vondrák Jan and Ron Cyril
DOI: 10.13168/AGG.2014.0007
Journal: Acta Geodynamica et Geomaterialia, Vol. 11, No. 3 (175), Prague 2014
Full Text: PDF file (5.1 MB)
Keywords: Rotation of the Earth, geophysical excitations, geomagnetic jerks, celestial pole offsets, free core nutation
Abstract: We use the most recent models of excitations by geophysical fluids (atmosphere, oceans) to derive their impact on the motion of the Earth spin axis in space – nutation. Celestial pole offsets (i.e., the differences between the observed nutation and the adopted IAU model) due to these geophysical excitations are computed for a non-rigid Earth model to account for the realistic Earth’s response. The results, corresponding to excitations provided by different agencies, are compared with the celestial pole offsets observed by Very Long-Baseline Interferometry. It is demonstrated that the celestial pole offsets excited by different models of geophysical fluids differ. Amplitudes based on European models ERA are larger than the observed ones, U.S. model NCEP/NCAR yields better agreement. If we apply re-initialization of the integration at epochs of geomagnetic jerks, the agreement between the integrated and observed values is much improved for all models studied.