Climate Dynamics

, Volume 41, Issue 2, pp 381–402 | Cite as

Decadal and long-term sea level variability in the tropical Indo-Pacific Ocean

  • A. G. Nidheesh
  • Matthieu Lengaigne
  • Jérôme Vialard
  • A. S. Unnikrishnan
  • H. Dayan


In this study, we analysed decadal and long-term steric sea level variations over 1966–2007 period in the Indo-Pacific sector, using an ocean general circulation model forced by reanalysis winds. The simulated steric sea level compares favourably with sea level from satellite altimetry and tide gauges at interannual and decadal timescales. The amplitude of decadal sea level variability (up to ~5 cm standard deviation) is typically nearly half of the interannual variations (up to ~10 cm) and two to three times larger than long-term sea level variations (up to 2 cm). Zonal wind stress varies at decadal timescales in the western Pacific and in the southern Indian Ocean, with coherent signals in ERA-40 (from which the model forcing is derived), NCEP, twentieth century and WASWind products. Contrary to the variability at interannual timescale, for which there is a tendency of El Niño and Indian Ocean Dipole events to co-occur, decadal wind stress variations are relatively independent in the two basins. In the Pacific, those wind stress variations drive Ekman pumping on either side of the equator, and induce low frequency sea level variations in the western Pacific through planetary wave propagation. The equatorial signal from the western Pacific travels southward to the west Australian coast through equatorial and coastal wave guides. In the Indian Ocean, decadal zonal wind stress variations induce sea level fluctuations in the eastern equatorial Indian Ocean and the Bay of Bengal, through equatorial and coastal wave-guides. Wind stress curl in the southern Indian Ocean drives decadal variability in the south-western Indian Ocean through planetary waves. Decadal sea level variations in the south–western Indian Ocean, in the eastern equatorial Indian Ocean and in the Bay of Bengal are weakly correlated to variability in the Pacific Ocean. Even though the wind variability is coherent among various wind products at decadal timescales, they show a large contrast in long-term wind stress changes, suggesting that long-term sea level changes from forced ocean models need to be interpreted with caution.


Sea level Steric level Decadal variability Climate 



The lead author is supported by financial assistance and research facilities of NIO-CSIR, India. The present work is a part of a project, funded by the Department of Science and Technology, Gov. of India. Jérôme Vialard and Matthieu Lengaigne are funded by Institut de Recherche pour le Développement (IRD) and did part of this work while visiting National Institute of Oceanography (NIO, India). The oceanic simulation in this paper was provided by the DRAKKAR project ( The satellite altimeter products were produced by Ssalto/Duacs and distributed by AVISO, with support from Cnes ( The tide-gauge data were made available through the Permanent Service for Mean Sea Level, PSMSL ( NCEP reanalysis data was provided by the NOAA/OAR/ESRL PSD, through their website at ( Support for the Twentieth Century Reanalysis Project dataset is provided by the U.S. DOE INCITE program, the Office of Biological and Environmental Research (BER), and by the National Oceanic and Atmospheric Administration (NOAA) Climate Program Office. We thank Benjamin Hamlington for providing a long-term reconstruction of sea level data, that we chose not to include in this paper. This is NIO contribution number 5206.


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Copyright information

© Springer-Verlag 2012

Authors and Affiliations

  • A. G. Nidheesh
    • 1
  • Matthieu Lengaigne
    • 2
    • 1
  • Jérôme Vialard
    • 2
  • A. S. Unnikrishnan
    • 1
  • H. Dayan
    • 2
  1. 1.Physical Oceanography DivisionNational Institute of Oceanography, CSIRDona PaulaIndia

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