Climate Dynamics

, Volume 37, Issue 9–10, pp 2045–2065 | Cite as

ENSO nonlinearity in a warming climate

  • J. BoucharelEmail author
  • B. Dewitte
  • Y. du Penhoat
  • B. Garel
  • S.-W. Yeh
  • J.-S. Kug


The El Niño Southern Oscillation (ENSO) is known as the strongest natural inter-annual climate signal, having widespread consequences on the global weather, climate, ecology and even on societies. Understanding ENSO variations in a changing climate is therefore of primordial interest to both the climate community and policy makers. In this study, we focus on the change in ENSO nonlinearity due to climate change. We first analysed high statistical moments of observed Sea Surface Temperatures (SST) timeseries of the tropical Pacific based on the measurement of the tails of their Probability Density Function (PDF). This allows defining relevant metrics for the change in nonlinearity observed over the last century. Based on these metrics, a zonal “see-saw” (oscillation) in nonlinearity patterns is highlighted that is associated with the change in El Niño characteristics observed in recent years. Taking advantage of the IPCC database and the different projection scenarios, it is showed that changes in El Niño statistics (or “flavour”) from a present-day climate to a warmer climate are associated with a significant change in nonlinearity patterns. In particular, in the twentieth century climate, the “conventional” eastern Pacific El Niño relates more to changes in nonlinearity than to changes in mean state whereas the central Pacific El Niño (or Modoki El Niño) is more sensitive to changes in mean state than to changes in nonlinearity. An opposite behaviour is found in a warmer climate, namely the decreasing nonlinearity in the eastern Pacific tends to make El Niño less frequent but more sensitive to mean state, whereas the increasing nonlinearity in the west tends to trigger Central Pacific El Niño more frequently. This suggests that the change in ENSO statistics due to climate change might result from changes in the zonal contrast of nonlinearity characteristics across the tropical Pacific.


ENSO Nonlinearity Global warming, El Niño Modoki Statistics Heavy-tails law 



This work has been supported by the Conseil Régional Midi-Pyrénées under contract No. 06001715. The authors would like to thank Pedro DiNezio for interesting discussions during the AGU of the America conference in Iguazu (Brazil) and two anonymous reviewers for their constructive comments. S.-W. Yeh has been supported from the Korea Meteorological Administration Research and Development Program under Grant RACS_2010-2006. J.-S. Kug is supported by Korea Meteorological Administration Research and Development Program under Grant CATER_2010-2007.


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Copyright information

© Springer-Verlag 2011

Authors and Affiliations

  • J. Boucharel
    • 1
    • 2
    Email author
  • B. Dewitte
    • 1
    • 3
  • Y. du Penhoat
    • 1
    • 3
  • B. Garel
    • 4
  • S.-W. Yeh
    • 5
  • J.-S. Kug
    • 6
  1. 1.Université de Toulouse; UPS (OMP-PCA), LEGOSToulouseFrance
  2. 2.School of Ocean and Earth Science and Technology, Department of MeteorologyUniversity of Hawai’i at ManoaHonoluluUSA
  3. 3.IRD, LEGOSToulouseFrance
  4. 4.Institut de Mathématiques de Toulouse (UPS)Université de Toulouse, INP-ENSEEIHTToulouseFrance
  5. 5.Department of Environmental Marine ScienceHanyang UniversityAnsanSouth Korea
  6. 6.Korea Ocean Research and Development InstituteAnsanSouth Korea

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