We are grateful to K. Weickmann for providing the torque dataset and for useful clarifications on its contents. The invaluable assistance of P. Nelson in handling the data, performing all calculations, and drafting the figures for the paper is acknowledged. Support for this research has been provided by the Climate Dynamics Program of the U.S. National Science Foundation under Grant ATM-9632559 and the NASA Solid Earth and Natural Hazards Program under Contract NAS5-97269.
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