Advances in Atmospheric Sciences

, Volume 25, Issue 3, pp 361–366 | Cite as

ENSO amplitude change in observation and coupled models

  • Qiong Zhang (张琼)
  • Yue Guan (关月)
  • Haijun Yang (杨海军)
Article

Abstract

Observations show that the tropical El Niño-Southern Oscillation (ENSO) variability, after removing both the long term trend and decadal change of the background climate, has been enhanced by as much as 60% during the past 50 years. This shift in ENSO amplitude can be related to mean state changes in global climate. Past global warming has caused a weakening of the Walker circulation over the equatorial Indo-Pacific oceans, as well as a weakening of the trade winds and a reduction in the equatorial upwelling. These changes in tropical climatology play as stabilizing factors of the tropical coupling system. However, the shallower and strengthening thermocline in the equatorial Pacific increases the SST sensitivity to thermocline and wind stress variabilities and tend to destabilize the tropical coupling system. Observations suggest that the destabilizing factors, such as the strengthening thermocline, may have overwhelmed the stabilizing effects of the atmosphere, and played a deterministic role in the enhanced ENSO variability, at least during the past half century. This is different from the recent assessment of IPCC-AR4 coupled models.

Key words

ENSO variability global warming thermocline Equatorial Pacific 

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Copyright information

© Science Press 2008

Authors and Affiliations

  • Qiong Zhang (张琼)
    • 1
  • Yue Guan (关月)
    • 1
    • 3
  • Haijun Yang (杨海军)
    • 2
  1. 1.State Key Laboratory of Numerical Modeling for Atmospheric Sciences and Geophysical Fluid Dynamics (LASG), Institute of Atmospheric PhysicsChinese Academy of SciencesBeijingChina
  2. 2.Department of Atmospheric Science, School of PhysicsPeking UniversityBeijingChina
  3. 3.Graduate University of the Chinese Academy of SciencesBeijingChina

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