Contribution of Oceanic and Atmospheric Excitations to the Chandler Wobble

Abstract

AbstractBy using the data series of oceanic and atmospheric angular momentum during 1985~1995, mean energies of the oceanic and atmospheric excitation in Chandler wobble band (CWB) are estimated and compared with that of the geodetically observed excitation. Results show that the variation of oceanic angular momentum (OAM) can provide about 64% of the excitation energy in CWB with a dominant contribution of the oceanic bottom pressure, while the excitation energies provided by atmospheric angular momenta (AAM (NCEP/NCAR) and AAM (JMA)) are about 23% and 214% in comparison with the observed one. Squared coherence, 0.52 (0.32 and 0.37), are also estimated between the observed excitation and the OAM (AAM (NCEP/NCAR) and AAM (JMA) excitations. Coherent phases show a lagging phase about 19° for OAM excitation, leading phases about 47° for AAM (NCEP/NCAR) and 19° for AAM (JMA), relative to the observed excitation, respectively. Analyses of some shorter (9 and 6 years.) and longer (16 and 39 years.) data series indicate that either the excitation energies, or the squared coherence are temporally variable, and their variability are of, in some extent, stochastic property.