Investigating ENSO sensitivity to mean climate in an intermediate model using a novel statistical technique

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Abstract

[1] Recent studies using general circulation models to project the response of ENSO to greenhouse warming find, despite a shift in the mean state toward a warmer climate, no significant change in the amplitude of ENSO. Here, an intermediate coupled model of tropical Pacific is shown to capture such insensitivity of ENSO to a change in mean climate. This is accomplished by systematically searching in the model parameter space for the configurations that enable the model to reproduce the observed variance, skewness, kurtosis, and autocorrelation of the Niño 3 index of the past 150 years. Three model configurations are identified to give similar approximation of Niño 3 index, which represent the realization of ENSO in different climate regimes.

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