Advertisement

Air and Water Contributions to Polar Motion Excitation

  • Clark R. Wilson
  • John Kuehne
Part of the International Association of Geodesy Symposia book series (IAG SYMPOSIA, volume 105)

Abstract

Modern space-geodetic observations show that the Earth’s polar motion occurs over a broad range of frequencies from below the Chandler frequency at fractions of a cycle per year (cpy), up to tens of cycles per year. Across this entire frequency band, the excitation sources for polar motion are only partially understood. Several studies have confirmed that meteorological effects, especially air mass redistribution, are correlated with observed polar motion within various frequency bands,(Wilson and Haubrich, 1976a, Wahr, 1982a, Eubanks et al, 1989), but the correlation has been imperfect, and the variance of observed air and water motion insufficient, suggesting that additional unknown sources must exist This paper reviews the studies of the contributions of air and water redistribution to polar motion excitation, with particular attention to estimates of the effects of continental water storage variation. Additional details are presented by Kuehne (1989). Because water can be stored on land in many forms, including ground water, ice, vegetation, and soil moisture, the estimates of water storage effects are difficult to obtain, but the general order of magnitude can be inferred from the widely available records of precipitation, in combination with other data and reasonable assumptions about climatological variation. The magnitude of the estimates suggests that continental water storage does not account for the unexplained portion of polar motion. A discrepancy in polar motion excitation persists over a broad band of frequencies including the annual frequency, where air and water are the certain cause. This implies that there are additional polar motion excitation sources in the atmosphere and oceans which remain unidentified.

Keywords

Water Storage Very Long Baseline Interferometry Polar Motion Annual Frequency Fourier Power Spectrum 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.

Preview

Unable to display preview. Download preview PDF.

Unable to display preview. Download preview PDF.

References

  1. Bureau Internationale de lHeure, Paris, Annual Reports 1979–1985Google Scholar
  2. Chao. B.F. and O’Conner, W., 1988, Global Surface-water-induced Seasonal Variations in the Earth’s Rotation and Gravitational Field, Geophysical Journal, 94, 263–270.CrossRefGoogle Scholar
  3. Dickman, S., 1988, Theoretical Investigation of the Oceanic Inverted Barometer Response, Journal of Geophysical Research, 93, B12.CrossRefGoogle Scholar
  4. Eubanks, T., Steppe, J., Dickey, J. Rosen, R. and Salstein, D., Causes of Rapid Motions of the Earth’s Pole, Nature, 334.Google Scholar
  5. Hinnov, L. and Wilson, C. 1987. An Estimate of the Water Storage Contribution to the Excitation of Polar Motion, Geophys. J. R. astron. Soc., 88, 437–459.CrossRefGoogle Scholar
  6. Jeffreys, H., 1916, Causes Contributory to the Annual Variation in Latitude, Mon. Not. R. astr. Soc., 76, 499–525.Google Scholar
  7. Korzoun, V., 1977. Atlas of World Water Balance, UNESCO Press, Paris.Google Scholar
  8. Kuehne, J., 1989. Water Storage Contributions to the Excitation of Polar Motion, Thesis, The University of Texas at Austin.Google Scholar
  9. Shaw, E., 1983. Hydrology in Practice, Van Nostrand Reindhold.Google Scholar
  10. Van Hylckama, T., 1970. Water Balance and Earth Unbalance, International Association of Scientific Hydrology, Proc. of the Reading Symp. World Water Balance, Publ. 92, AIHS-UNESCO.Google Scholar
  11. Wahr, J., 1982a. The effects of the atmosphere and Oceans on the Earth’s Wobble, I, Geophys. J. R. astr. Soc., 70, 349–372.CrossRefGoogle Scholar
  12. Wahr, J., 1982b. The Effects of the Atmosphere and Oceans on the Earth’s Wobble and on the Seasonal Variations in the Length of Day, II. Geophys. J. R. astro. Soc., 74, 451–487.Google Scholar
  13. Wilson, C. and Haubrich, R. 1976a, Meteorological Excitation of the Earth’s Wobble, Geophys. JJl. astr. Soc., 46, 707–743.CrossRefGoogle Scholar
  14. Wilson, C. and Haubrich, R. 1976b. Atmospheric Contributions to the Excitation of the Earth’s Wobble, 1901-1970, Geophys. J. R. astr. Soc., 46, 745–760.CrossRefGoogle Scholar
  15. Wilson, C. 1985, Discrete Polar Motion Equations, Geophys. J. R. astr. Soc., 80, 551–554.CrossRefGoogle Scholar
  16. Willmott, C., Rowe, C, and Mintz, Y. 1985. Climatology of the Terrestrial Seasonal Water Cycle, Journal of Climatology, 5, 589–606.CrossRefGoogle Scholar
  17. Yumi, S., and Yokoyama, L., 1980. Results of the ILS in a homogeneous system 1899.9-1979. 0, CBIPMS, International Latitude Observatory of Mizusawa, Japan.Google Scholar

Copyright information

© Springer-Verlag New York Inc. 1990

Authors and Affiliations

  • Clark R. Wilson
    • 1
  • John Kuehne
    • 1
  1. 1.Center for Space Research, Institute for Geophysics Department of Geological SciencesThe University of Texas at AustinAustinUSA

Personalised recommendations