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Atmospheric Excitation of Polar Motion

Published online by Cambridge University Press:  12 April 2016

David Salstein
David Salstein*
Affiliation:
Atmospheric and Environmental Research, Inc., 840 Memorial Drive, Cambridge, MA 02139USA

Abstract

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Variations in the angular momentum of the atmosphere in the equatorial plane due to shifts in air mass distribution and changing winds impact the orientation of Earth so that motions of the pole occur on a broad range of time scales. The wind terms have notable diurnal fluctuations, which appear as a tidal signature. Subseasonal fluctuations of the pole are shown to be related to the atmospheric signal on scales as short as at least a week, according to a coherency analysis. Atmospheric mass fluctuations over certain regions, such as Eurasia and North America, appear to be more responsible for rapid polar motions than are those elsewhere, and may be related to known climate modes. On the other hand, atmospheric pressure fluctuations over the ocean are counteracted in large measure by a sea level response, due to an inverted barometer relationship. Ocean forcing from model results assist in narrowing the differences in the geodetic and atmospheric budgets. Efforts to assess dynamic forecasts of the atmospheric polar motion excitations have demonstrated positive skill out to at least 10 days for the mass term.

Type
Part 5. Chandler and Annual Polar Motion: Observations and Excitation
Information
International Astronomical Union Colloquium , Volume 178: Polar Motion: Historical and Scientific Problems , 2000 , pp. 437 - 446
Copyright
Copyright © Astronomical Society of the Pacific 2000

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