Chinese Journal of Oceanology and Limnology

, Volume 28, Issue 2, pp 344–353 | Cite as

Effect of low-frequency Rossby wave on thermal structure of the upper southwestern tropical Indian Ocean

  • Junqiao Feng (冯俊乔)
  • Xuezhi Bai (白学志)
  • Yongli Chen (陈永利)
  • Dunxin Hu (胡敦欣)
Physics

Abstract

We investigate the influence of low-frequency Rossby waves on the thermal structure of the upper southwestern tropical Indian Ocean (SWTIO) using Argo profiles, satellite altimetric data, sea surface temperature, wind field data and the theory of linear vertical normal mode decomposition. Our results show that the SWTIO is generally dominated by the first baroclinic mode motion. As strong downwelling Rossby waves reach the SWTIO, the contribution of the second baroclinic mode motion in this region can be increased mainly because of the reduction in the vertical stratification of the upper layer above thermocline, and the enhancement in the vertical stratification of the lower layer under thermocline also contributes to it. The vertical displacement of each isothermal is enlarged and the thermal structure of the upper level is modulated, which is indicative of strong vertical mixing. However, the cold Rossby waves increase the vertical stratification of the upper level, restricting the variability related to the second baroclinic mode. On the other hand, during decaying phase of warm Rossby waves, Ekman upwelling and advection processes associated with the surface cyclonic wind circulation can restrain the downwelling processes, carrying the relatively colder water to the near-surface, which results in an out-of-phase phenomenon between sea surface temperature anomaly (SSTA) and sea surface height anomaly (SSHA) in the SWTIO.

Keyword

Rossby wave vertical baroclinic mode Argo sea surface height anomaly (SSHA) sea surface temperature anomaly (SSTA) 

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References

  1. Annamalai H, Murtugudde, R. Potemra J. et al. 2003. Coupled dynamics over the Indian Ocean: spring initiation of the zonal mode. Deep-Sea Res., II 50: 2 305–2 330.CrossRefGoogle Scholar
  2. Birol F, Morrow R. 2001. Source of the baroclinic waves in the southeast Indian Ocean. J. Geophys. Res., 106: 9 145–9 160.CrossRefGoogle Scholar
  3. Chambers, D. P., B. Tapley D. Stewart, R. H. 1999. Anomalous warming in the Indian Ocean coincident with El Niño. J. Geophys. Res., 104: 3 035–3 047.CrossRefGoogle Scholar
  4. Chao J P, Chao Q C, Liu L. 2006. The ENSO events in the tropical Pacific and dipole events in the Indian Ocean. Acta Meteorologica Sinica, 20(2): 223–231.Google Scholar
  5. Cipollini, P., Cromwell, D. Jones M. S. et al. 1997. Concurrent altimeter and infrared observations of Rossby wave propagation near 34°N in the Northeast Atlantic. Geophys. Res. Lett., 24(8): 889–892.CrossRefGoogle Scholar
  6. Dewitte, B., Reverdin G. Maes, C. 1999. Vertical structure of an OGCM simulation of the equatorial Pacific Ocean in 1985–94. J. Phys. Oceanogr., 29: 1 542–1 570.CrossRefGoogle Scholar
  7. Dewitte B, Illig S, Parent L. et al. 2003. Tropical Pacific baroclinic mode contribution and associated long waves for the 1994–1999 period from an assimilation experiment with altimetric data. J. Geophys. Res., 108(C4): 3 121–3 138.CrossRefGoogle Scholar
  8. Giese B S, Harrison D E, 1990. Aspects of the Kelvin wave response to episodic wind forcing. J. Geophys. Res., 95(C5): 7 289–7 312.CrossRefGoogle Scholar
  9. Gill A E. 1982a. Atmosphere-Ocean dynamics. Academic Press. p. 159–165.Google Scholar
  10. Gill A E. 1982b. Changes in thermal structure of the equatorial Pacific during the 1972 El Niño as revealed by bathythermograph observations. J. Phys. Oceanog., 12: 1 373–1 387.CrossRefGoogle Scholar
  11. Jochum, M. Murtugudde, R. 2005. Internal variability of Indian SST. J. Climate, 18: 3 726–3 738.Google Scholar
  12. Klein, S. A., B. J. Soden and N.-C. Lau, 1999. Remote sea surface temperature variations during ENSO: Evidence for a tropical atmospheric bridge. J. Climate, 12: 917–932.CrossRefGoogle Scholar
  13. Liu L, Yu W D 2006. Connection between tropical Indian Ocean dipole event and subtropical Indian Ocean dipole event. Advances in Marine Science, 24(3): 301–306. (in Chinese with English abstract)Google Scholar
  14. Liu, Z. Y., 1999. Planetary waves in thermocline circulation: non-Doppler-shift mode, advective mode and green mode. Quart. J. Roy. Meteor. Soc 125: 1 315–1 339.CrossRefGoogle Scholar
  15. Lu J, Qiao F L, Wei Z X et al. 2008. Study on distribution of mixed layer depth in the world ocean in summer-comparison between Argo data and Levitus Data. Advances In Marine Science, 26(2): 145–155. (in Chinese with English abstract)Google Scholar
  16. Masumoto Y, Meyers G. 1998. Forced Rossby waves in the southern tropical Indian Ocean. J. Geophys. Res., 103: 27 589–27 602.CrossRefGoogle Scholar
  17. Montégut D, Madec G A, Fischer et al. 2004. Mixed layer depth over the global ocean: an examination of profile data and a profile-based climatology. J. Geophys. Res., 109:C12003. doi:10.1029/2004JC002378.CrossRefGoogle Scholar
  18. Moon B K, Yeh S W, Dewitte B et al. 2004. Vertical structure variability in the equatorial Pacific before and after the Pacific climate shift of the 1970s. Geophys. Res. Lett., 31: L03203, doi:10.1029/2003GL018829.CrossRefGoogle Scholar
  19. Murtugudde R, Busalacchi A J. 1999. Interannual variability of the dynamics and thermodynamics of the tropical Indian Ocean. J. Climate, 12: 2 300–2 326.CrossRefGoogle Scholar
  20. Pedlosky J, 2003. Waves in the ocean and atmosphere: introduction to wave dynamics. Springer. p. 183–191.Google Scholar
  21. Picaut J, Laurence S. 1993. Influence of density stratification and bottom depth on vertical mode structure functions in the tropical Pacific. J. Geophys. Res., 98(C8): 1 4727–1 4738.CrossRefGoogle Scholar
  22. Qian W H, Hu H R, Deng Y. 2002. Signals of interannual and interdecadal variability of air-sea interaction in the basin-wide Indian Ocean. Atmosphere-Ocean, 40(3): 293–311.CrossRefGoogle Scholar
  23. Qian W H, Hu H R, Zhu Y F. 2003. Thermocline oscillation and warming event in the tropical Indian Ocean. Atmosphere-Ocean 41(3): 241–258.CrossRefGoogle Scholar
  24. Rao S A, Behera S K. 2005. Subsurface influence on SST in the tropical Indian Ocean: structure and interannual variability. Dyn. Atmos. Oceans 39: 103–135.CrossRefGoogle Scholar
  25. Saji N H, Goswami B N, Vinayachandran P N et al. 1999. A dipole mode in the tropical Indian Ocean. Nature, 401: 360–363.Google Scholar
  26. Sun Z Y, Liu L, Yu W D. 2007. Study on seasonal variations in the tropical Indian Ocean mixed layer depth derived from Argo float data. Advances in Marine Science, 25: 280–288. (in Chinese with English abstract)Google Scholar
  27. Xie S P, Annamalai, H. Schott F. A. et al. 2002. Structure and mechanisms of South Indian Ocean climate variability. J. Climate 15: 864–878.CrossRefGoogle Scholar
  28. Ye Z M, Zhang M 2004. Numerical calculation of vertical modes of Rossby internal wave for Argo station in the mid-low-latitude Pacific Ocean. Marine Science Bulletin 23(6): 1–7. (in Chinese with English abstract)Google Scholar
  29. Yuan D L, Liu H L. 2008. Long wave dynamics of sea level variations during Indian Ocean Dipole events. J. Phys. Oceaogr. doi: 10.1175/2008JPO3900.1.Google Scholar
  30. Zhou L, Murtugudde R, Jochum M. 2008. Seasonal influence of Indonesian Throughflow in the southwestern Indian Ocean. J.Phys. Oceaogr. 28: 1 529–1 541.Google Scholar

Copyright information

© Chinese Society for Oceanology and Limnology, Science Press and Springer Berlin Heidelberg 2010

Authors and Affiliations

  • Junqiao Feng (冯俊乔)
    • 1
    • 2
    • 3
  • Xuezhi Bai (白学志)
    • 1
    • 2
  • Yongli Chen (陈永利)
    • 1
    • 2
  • Dunxin Hu (胡敦欣)
    • 1
    • 2
  1. 1.Institute of OceanologyChinese Academy of SciencesQingdaoChina
  2. 2.Key Laboratory of Ocean Circulation and WavesChinese Academy of SciencesQingdaoChina
  3. 3.Graduate University of Chinese Academy of SciencesBeijingChina

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