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The pole tide is the response of earth's oceans to a free wobble. It has been widely assumed that the response is an equilibrium one; such a response would involve no dissipation of wobble energy and would result in a tide of small amplitude, roughly 1/2 cm. An equilibrium tide would force the path of the wobbling rotation pole to be slightly elliptical (~0.01 ellipticity) and would contribute about 1 month to the observed 14-month Chandler Wobble period. Yet a greatly enhanced pole tide, with amplitude typically 5 times the predicted equilibrium value, has long been observed in the North and Baltic seas. In recent years much evidence has been gathered (through diverse data analysis techniques) which suggests that the global oceanic response is also nonequilibrium. In this paper a theory which accounts for the effects of an arbitrary tide on rotation has been developed and applied to situations of uniform global enhancement and enhancement in the North and Baltic seas only. Pole tide amplitudes up to 10 times equilibrium and phase lags as much as 4 1/2 months behind equilibrium were considered. In the case of North/Baltic seas enhancement, conservation of mass leads to a 'pumping phenomenon' whose effect on the oceans worldwide is as significant as the local enhancement itself. The theory only requires an assumption that the time and space dependence of the tide amplitude T can be separated using complex notation, T=Xn+X*n*, where X and n represent the spatial and temporal variation of the tide; n is related by a phase lag to the instantaneous rotation pole position. Such separation of variables has been shown to hold in the case of an equilibrium tide. The results support the hypothesis that the oceans are capable of damping the Chandler Wobble; damping times between 2 and 80 years are likely, depending on the degree of enhancement. This reomves the need to postulate that the mantle is anomalously anelastic at frequencies below the seismic band. It is also possible that the oceanic contribution to the Chandler period greatly exceeds 1 month; that would imply the fluid core response to wobble is more limited than previously thought, since the contributions of both the core and the oceans must yield a 14-month Chandler period. This could have serious consequences regarding the outer core's density stratification, which governs the dynamic core response to wobble. |