Journal of the Indian Society of Remote Sensing

, Volume 40, Issue 4, pp 679–688 | Cite as

Sea Surface Height Variability in the Tropical Indian Ocean: Steric Contribution

  • M. Salim
  • R. K. NayakEmail author
  • D. Swain
  • V. K. Dadhwal
Research Article


Variability of Sea level and its steric contribution in the Tropical Indian Ocean (TIO) was studied based on 15 years (1993–2007) satellite altimeter observations of sea surface height (SSH) anomaly and steric height (STH) anomaly computed using temperature and salinity fields obtained from Simple Ocean Data Assimilation (SODA) product. Complex Empirical Orthogonal Function (CEOF) analysis was carried out to decompose variability of SSH and STH into various modes to examine the coherency between them. It is revealed that both the parameters exhibit variability in all the time scales. First three major modes of CEOF corresponds to 90% and 84% of the total variability of SSH and STH respectively. There exists strong coherence between the respective CEOF modes of SSH and STH. The first mode of CEOF contributes around ~50% of the total signal corresponds to the annual cycle exhibit large variability in the western Arabian Sea along the Somali and Arabia Coast, latitudinal strip between 2 and 10°N extending from Somali-coast to the west coast of India, coastal oceans around India, and the south eastern TIO. The second CEOF with 25% of total signal contains mixed signature of intra-seasonal and inter-annual periodicities. This exhibit large amplitude in the central south TIO, western and eastern parts of Equatorial Indian Ocean (EIO). Computed long term linear growth rate of sea level anomaly suggests that increase of sea level varies from small (1–3 mm yr−1) in the north TIO to large (8 mm yr−1) in the south TIO. Further analysis suggests that SSH trend in the south TIO was mostly governed by steric contribution while the variability of SSH trend in the north TIO could be explained partially by the variability in STH.


Satellite altimeter Sea surface height Indian Ocean El Nino Inter-annual variability 



This work has been carried out under ISRO-CNES SARAL-ALTIKA science application program. One of the authors, MS is supported by a research fellowship under the program. We acknowledge AVISO and SODA team for making available the Sea Surface Data and SODA for time series T/S profiles of the global ocean.


  1. Adamec, D., & O’Brein, J. J. (1978). The seasonal upwelling in the Gulf of Guinea due to remote forcing. Journal of Physical Oceanography, 8, 1050–1060.CrossRefGoogle Scholar
  2. Antonov, J. I., Levitus, S., & Boyer, T. P. (2002). Steric sea level variations during 1957–1994: Importance of salinity. Journal of Geophysical Research, 107. doi: 10.1029/2001JC000964.
  3. AVISO. (1996). AVISO user handbook: Merged TOPEX/Poseidon products, ed. 3.0, AVI-NT-02-101-CN, July 1996, Toulouse, France.Google Scholar
  4. Cabanes, C., Cazenave, A., & Le Provost, C. (2001). Sea level rise during past 40 years determined from satellite and in situ observations. Science, 294(5543), 840–842. doi: 10.1126/science.1063556.CrossRefGoogle Scholar
  5. Carton, J. A., Giese, B. S., & Grodsky, S. A. (2005). Sea level rise and the warming of th oceans in the Simple Ocean Data Assimilation (SODA) ocean reanalysis. Journal of Geophysical Research, 110, C09006. doi: 10.1029/2004JC002817.CrossRefGoogle Scholar
  6. Cazenave, A., & Nerem, R. S. (2004). Present-day sea level change: Observations and causes. Reviews of Geophysics, 42, RG3001. doi: 10.1029/2003RG000139.CrossRefGoogle Scholar
  7. Cazenave, A., Dominh, K., Gennero, M. C., & Ferret, B. (1998). Global mean sea level changes observed by Topex-Poseidon and ERS-1. Physics and Chemistry of the Earth, 23(9–10), 1069–1075. doi: 10.1016/S0079-1946(98)00146-3.CrossRefGoogle Scholar
  8. Clarke, A. J., & Liu, X. (1993). Observations and dynamics of semi-annual and annual sea levels near the eastern equatorial Indian Ocean boundary. Journal of Physical Oceanography, 23, 386–399.CrossRefGoogle Scholar
  9. Ducet, N., Le Traon, P. Y., & Reverdin, G. (2000). Global high-resolution mapping of ocean circulation from TOPEX/Poseidon and ERS-1 and-2. Journal of Geophysical Research, 105, 19 477–19 498.CrossRefGoogle Scholar
  10. Fu, L.-L. (2010). Determining ocean circulation and sea level from satellite altimetry: Progress and challenges. In V. Barale, J. F. R. Gower and L. Alberotanza (Eds.), Oceanography from space (pp. 147–163). Springer, Netherlands, 978-90-481-8681-5.Google Scholar
  11. Gill, A. E. (1982). Atmosphere-Ocean dynamics (p. 662). London: Academic.Google Scholar
  12. Hannachi, A., Jolliffe, I. T., & Stephenson, D. B. (2010). Empirical orthogonal functions and related techniques in atmospheric science: A review. International Journal of Climatology, 27(1967), 1119–1152.Google Scholar
  13. Hariharan, H., Gribok, A., Abidi, M. A., & Koschan, A. (2006). Image fusion and enhancement via empirical mode decomposition. Journal of Pattern Recognition Research, 1, 16–32.Google Scholar
  14. Holgate, S. J., & Woodworth, P. L. (2004). Evidence for enhanced coastal sea level rise during the 1990s. Geophysical Research Letters, 31, L07305. doi: 10.1029/2004GL019626.CrossRefGoogle Scholar
  15. Huang, N. E., Shen, Z., Long, S. R., Wu, M. C., Shih, H. H., Zheng, Q., Yen, N.-C., Tung, C. C., & Liu, H. H. (1998). The empirical mode decomposition and the Hilbert spectrum from nonlinear and non-stationary time series analysis. Proceedings of the Royal Society of London - Series A, 454, 903–995.CrossRefGoogle Scholar
  16. Jensen, T. G. (1991). Modelling the seasonal under current in the Somali current system. Journal of Geophysical Research, 96, 22 151–22 167.Google Scholar
  17. Landerer, F. W., Jungclaus, J. H., & Marotzke, J. (2007). Regional dynamic and steric sea level change in response to the IPCC-A1B scenario. Journal of Physical Oceanography, 37, 296–312.CrossRefGoogle Scholar
  18. Levitus, S. (1990). Interpentadal variability of steric sea-level and geopotential thickness of the North-Atlantic Ocean, 1970–1974 versus 1955–1959. Journal of Geophysical Research, 95, 5233–5238.CrossRefGoogle Scholar
  19. McCreary, J. P., Kundu, P. K., & Molinari, R. L. (1993). A numerical investigation of dynamics, thermodynamics and mixed layer processes in the Indian ocean. Progress in Oceanography, 31, 181–244.CrossRefGoogle Scholar
  20. Potemra, J. T., Luther, M. E., & O’Brien, J. (1991). The seasonal circulation of the upper ocean in the Bay of Bengal. Journal of Geophysical Research, 96(C7), 12 667–12 683.CrossRefGoogle Scholar
  21. Rio, M-H, Schaeffer P., Moreaux G., Lemoine J.-M., Bronner E. (2009). A new mean dynamic topography computed over the global ocean from GRACE data, altimetry and in-situ measurements. Poster communication at OceanObs09 symposium, 21-25 September 2009, Venice.Google Scholar
  22. Sakova, I. V., Meyers, G., & Coleman, R. (2006). Interannual variability in the Indian cean using altimeter and IX1-expendable bathy-thermograph (XBT) data: Does the 18-month signal exist? Geophysical Research Letters, 33, L20603. doi: 10.1029/2006GL027117.CrossRefGoogle Scholar
  23. Shankar, D., Aparna, S. G., McCreary, J. P., Suresh, I., Neetu, S., Durand, F., Shenoi, S. S. C., & Al Saafani, M. A. (2010). Minima of interannual sea-level variability in the Indian ocean. Progress in Oceanography, 84, 225–241.CrossRefGoogle Scholar
  24. Shenoi, S. S. C., Shankar, D., & Shetye, S. R. (1999). On the sea surface temperature high in in the Lakshadweep Sea before the onset of the southwest monsoon. Journal of Geophysical Research, 104, 15703–15712.CrossRefGoogle Scholar
  25. Willis, J. K., Roemmich, D., & Cornuelle, B. (2004). Interannual variability in upper ocean heat content, temperature, and thermosteric expansion on global scales. Journal of Geophysical Research, 109, C12036. doi: 10.1029/2003JC002260.CrossRefGoogle Scholar
  26. Yang, J., Yu, L., Koblinsky, C., & Adamec, D. (1998). Dynamics of the seasonal variations in the Indian ocean from TOPEX/POSEIDON sea surface height and an ocean model. Geophysical Research Letters, 25(11), 1915–1918.CrossRefGoogle Scholar
  27. Yu, L., O’Brien, J. J., & Yang, J. (1991). On the remote forcing of the circulation in the Bay of Bengal. Journal of Geophysical Research, 96, 20 449–20 454.CrossRefGoogle Scholar

Copyright information

© Indian Society of Remote Sensing 2012

Authors and Affiliations

  • M. Salim
    • 1
  • R. K. Nayak
    • 1
    Email author
  • D. Swain
    • 1
  • V. K. Dadhwal
    • 1
  1. 1.National Remote Sensing CentreISROHyderabadIndia

Personalised recommendations