What Controls ENSO-Amplitude Diversity in Climate Models?

Wengel, Christian, Dommenget, Dietmar, Latif, Mojib, Bayr, Tobias and Vijayeta, A. (2018) What Controls ENSO-Amplitude Diversity in Climate Models? Geophysical Research Letters . DOI 10.1002/2017GL076849.

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Supplementary data:

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.

Document Type: Article
Additional Information: The CMIP5 data output is available at http://www. ipcc-data.org/sim/gcm_monthly/AR5/Reference-Archive.html.
Keywords: El Niño; stochastic forcing; ENSO-amplitude diversity; CMIP5; recharge oscillator; Bjerknes Stability index
Research affiliation: OceanRep > The Future Ocean - Cluster of Excellence > FO-R09
OceanRep > GEOMAR > FB1 Ocean Circulation and Climate Dynamics > FB1-ME Maritime Meteorology
OceanRep > SFB 754
OceanRep > The Future Ocean - Cluster of Excellence
OceanRep > SFB 754 > A1
Refereed: Yes
DOI etc.: 10.1002/2017GL076849
ISSN: 0094-8276
Projects: Future Ocean, SACUS, PREFACE, SFB754
Date Deposited: 06 Mar 2018 07:09
Last Modified: 06 Mar 2018 10:22
URI: http://eprints.uni-kiel.de/id/eprint/42161

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