Detecting Excitation Source of the Chandler Wobble

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The earth is a dynamically coupled system of atmosphere, hydrosphere, mantle and core under conservation of angular momentum. There are many observational facts that global changes in solid-earth system including core as well as in atmosphere-hydrosphere system have been closely connected with angular momentum exchanges between the above two systems.In order to explain these facts, this paper presents a model that a non-linear feedback system of atmosphere-hydrosphere having a period-length doubling harmonics with the two typical spherical harmonics modes which excite the wobble and LOD controls excitation of the Chandler wobble and hence causes global changes in the solid-earth system such as change in worldwide seismic activity and geomagnetic change with periods of decades.The observational facts reveal that the earth's dynamic coupling system causing these global changes may be closed in a period of about 40 years. The model can straight lead to a previous view that the present day climatic fluctuation closely correlated with the decades variations of the lengthof day and the wobble amplitude.