A nonlinear framework for advancing our understanding of ENSO in climate models

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Tuesday, 6 January 2015: 1:30 PM
122BC (Phoenix Convention Center - West and North Buildings)
Pedro N. DiNezio, University of Hawaii, Honolulu, HI

Coupled general circulation models (CGCMs) have achieved an impressive degree of realism in their simulation of the El Nino/Southern Oscillation (ENSO) phenomenon, including the broad 3-6 year spectral peak, decadal variation in amplitude and frequency, and asymmetries in duration and magnitude between El Nino and La Nina. Understanding the dynamics giving rise to these features, as well as those governing the response of ENSO to anthropogenic global warming has become a challenge onto itself. In my talk I will present a non-linear framework for the dynamics of ENSO and its interaction with the seasonal cycle. The methodology estimates nonlinear and seasonally-dependent feedbacks from CGCM output and integrates them into a nonlinear delayed oscillator (NDO) model for ENSO. Despite it is simplicity; the NDO captures all of the features of ENSO described above. I will illustrate the power of this method for addressing the following problems: 1) the dynamics and predictability of multi-year La Nina events, and 2) the emergence of ENSO's response to global warming.