Contribution of Non-Tidal Oceanic Mass Variations to Polar Motion Determined from Space Geodesy and Ocean Data

  • F Göttl
  • F Seitz
Part of the International Association of Geodesy Symposia book series (IAG SYMPOSIA, volume 133)


In order to assess the contribution of non-tidal oceanic mass changes to polar motion, equatorial oceanic excitation functions are determined from combinations of space geodetic techniques and ocean data. Satellite altimetry provides accurate information on sea level anomalies (SLA) which are caused by mass and volume changes of seawater. Since Earth rotation is solely affected by mass variations the volume (steric) effect has to be reduced from the observations in order to infer oceanic contributions to Earth rotation. Oceanic polar motion excitations from reduced SLA are compared with respective results from ocean models. Contributions of ocean currents, atmospheric and hydrological effects are added in order to validate the oceanic excitations from altimetry with independent geodetic observations which reflect the integral effect of a multitude of geophysical processes in the Earth system. This requires an investigation of accuracy and consistency of the combined data sets. The study reveals that model-only combinations of atmospheric, oceanic and hydrological excitations agree better with geodetic observations than combinations which include excitations from altimetry. Possible reasons could be errors in the steric reduction of SLA and/or the compensation of erroneous patterns in atmosphere data by numerical ocean models


Oceanic mass variations Polar motion Satellite altimetry Steric effect 


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  1. Antonov, J.I., R.A. Locarnini, T.P. Boyer et al. (2006). World Ocean Atlas 2005. Volume 2: Salinity. S. Levitus, Ed. NOAA Atlas NESDIS 62, U.S. Government Printing Office, Washington, D.C., pp. 182Google Scholar
  2. Chambers, D.P. (2006). Observing seasonal steric sea level variations with GRACE and satellite altimetry. J. Geophys. Res., 111, 10.1029/2005JC002914CrossRefGoogle Scholar
  3. Chen, J.L., C.R. Wilson, R.J. Eanes et al. (2000). A new assessment of long-wavelength gravitational variations. J. Geophys. Res., 105, 0148-0227/00/2000JB900115Google Scholar
  4. Fofonoff, N.P. and R.C. Millard (1983). Algorithms for computation of fundamental properties of seawater. Unesco Technical Papers in Marine Science, 44Google Scholar
  5. Gross, R.S. (1992). Correspondence between theory and observations of polar motion. Geophys. J. Int., 109, pp. 162–170CrossRefGoogle Scholar
  6. Gross, R.S. (2007). Earth rotation variations – long period. in: Treatise on Geophysics, Volume 3 – Geodesy, Elsevier, in pressGoogle Scholar
  7. Gross, R.S., I. Fukumori, and D. Menemenlis (2005). Atmospheric and oceanic excitation of decadal-scale Earth orientation variations. J. Geophys. Res., 110, B09405CrossRefGoogle Scholar
  8. Ishii, M., M. Kimoto, K. Sakamoto et al. (2006). Steric sea level changes estimated from historical ocean subsurface temperature and salinity analyses. J. Oceanography, 62, pp. 155–170CrossRefGoogle Scholar
  9. Kalnay, E., M. Kanamitsu, R. Kistler et al. (1996). The NCEP/NCAR 40-year reanalysis project. Bull. Amer. Meteor. Soc., 77, pp. 437–471CrossRefGoogle Scholar
  10. Locarnini, R.A., A.V. Mishonov, J.I. Antonov et al. (2006). World Ocean Atlas 2005. Volume 1: Temperature. S. Levitus, Ed. NOAA Atlas NESDIS 61, U.S. Government Printing Office, Washington, D.C., pp. 182Google Scholar
  11. Milly, P.C.D and A.B. Shmakin (2002). Global modeling of land water and energy balances Part I: the land dynamics (LaD) model. J. Hydrometeorology, 3, pp. 283–299CrossRefGoogle Scholar
  12. Thomas, M., J. Sündermann and E. Maier-Reimer (2001). Consideration of ocean tides in an OGCM and impacts on subseasonal to decadal polar motion excitation. Geophys. Res. Lett., 28(12), pp. 2457–2460CrossRefGoogle Scholar
  13. Zhou, Y.H., D.A. Salstein and J.L. Chen (2006). Revised atmospheric excitation function series related to Earth’s variable rotation under consideration of surface topography. J. Geophys. Res., 111, 10.1029/2005JD006608Google Scholar

Copyright information

© Springer-Verlag Berlin Heidelberg 2009

Authors and Affiliations

  • F Göttl
    • 1
  • F Seitz
    • 2
  1. 1.Deutsches Geodätisches Forschungsinstitut (DGFI)Germany
  2. 2.Earth Oriented Space Science and Technology (ESPACE)Technische Universität MunchenD-80290 MunichGermany

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