What Controls ENSO-Amplitude Diversity in Climate Models?

C. Wengel, D. Dommenget, M. Latif, T. Bayr, A. Vijayeta

Research output: Contribution to journalArticleResearchpeer-review

6 Citations (Scopus)

Abstract

Climate models depict large diversity in the strength of the El Niño/Southern Oscillation (ENSO) (ENSO amplitude). Here we investigate ENSO-amplitude diversity in the Coupled Model Intercomparison Project Phase 5 (CMIP5) by means of the linear recharge oscillator model, which reduces ENSO dynamics to a two-dimensional problem in terms of eastern equatorial Pacific sea surface temperature anomalies (T) and equatorial Pacific upper ocean heat content anomalies (h). We find that a large contribution to ENSO-amplitude diversity originates from stochastic forcing. Further, significant interactions exist between the stochastic forcing and the growth rates of T and h with competing effects on ENSO amplitude. The joint consideration of stochastic forcing and growth rates explains more than 80% of the ENSO-amplitude variance within CMIP5. Our results can readily explain the lack of correlation between the Bjerknes Stability index, a measure of the growth rate of T, and ENSO amplitude in a multimodel ensemble.

Original languageEnglish
Pages (from-to)1989-1996
Number of pages8
JournalGeophysical Research Letters
Volume45
Issue number4
DOIs
Publication statusPublished - 28 Feb 2018

Keywords

  • Bjerknes Stability index
  • CMIP5
  • El Niño
  • ENSO-amplitude diversity
  • recharge oscillator
  • stochastic forcing

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