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What Controls ENSO‐Amplitude Diversity in Climate Models?
Author(s) -
Wengel C.,
Dommenget D.,
Latif M.,
Bayr T.,
Vijayeta A.
Publication year - 2018
Publication title -
geophysical research letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.007
H-Index - 273
eISSN - 1944-8007
pISSN - 0094-8276
DOI - 10.1002/2017gl076849
Subject(s) - amplitude , forcing (mathematics) , climatology , el niño southern oscillation , environmental science , pacific decadal oscillation , coupled model intercomparison project , oscillation (cell signaling) , climate model , atmospheric sciences , physics , geology , climate change , oceanography , quantum mechanics , biology , genetics
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.