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International Journal of Geophysics
Volume 2011, Article ID 174396, 10 pages
http://dx.doi.org/10.1155/2011/174396
Research Article

Hydrological Excitation of Polar Motion Derived from GRACE Gravity Field Solutions

1CNRS/UMR8630, Observatoire de Paris, 61 avenue de l'Observatoire, 75014 Paris, France
2Space Research Center, Polish Academy of Sciences, Bartycka 18 A, 00-716 Warsaw, Poland

Received 1 October 2010; Accepted 29 March 2011

Academic Editor: Petr Vaníček

Copyright © 2011 L. Seoane et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

The influence of the continental water storage on the polar motion is not well known. Different models have been developed to evaluate these effects and compared to geodetic observations. However, previous studies have shown large discrepancies mainly attributed to the lack of global measurements of related hydrological parameters. Now, from the observations of the GRACE mission, we can estimate the polar motion excitation due to the global hydrology. Data processing of GRACE data is carried out by several centers of analysis, we focus on the new solution computed by the Groupe de Recherche de Géodésie Spatiale. At annual scales, excitations derived from GRACE data are in better agreement with geodetic observations than models estimates. The main contribution to the hydrological excitation comes from the monsoon climates regions where GRACE and models estimates are in a very good agreement. Still, the effect of the north high latitudes regions, where the principal areas of snow cover are found, cannot be neglected. At these regions, GRACE and models estimated contributions to polar motion excitations show significant discrepancies. Finally, GRACE-based excitations reveal the possible influence of water storage variations in exciting polar motion around the frequency of 3 cycles per year.