Chaotic dynamics of recharge–discharge El Niño–Southern Oscillation (ENSO) model
IIC, South Campus, University of Delhi, Benito-Juarez Road, 110021, New Delhi, Delhi, India
2 Nonlinear Dynamics Research Lab, University School of Basic and Applied Studies, Guru Gobind Singh Indraprastha University, Sec-16C, Dwarka, 110078, New Delhi, Delhi, India
Accepted: 29 November 2022
Published online: 9 December 2022
This paper deals with the study of chaotic dynamics in recharge–discharge oscillator model of El Niño Southern Oscillation (ENSO). A solar-forced recharge–discharge model for ENSO has been considered in the study. The model equations are transformed to a van der Pol–Duffing oscillator model with an 11-year solar forcing. From numerical simulation, the oscillator model with periodic forcing is observed to transit to chaos as the forcing is increased. On varying amplitude of periodic forcing (F), multiple transition from regular to chaos and chaos to regular states through several transition windows is observed in the bifurcation plot. For particular values of the F, the phase plot and recurrence plot show the regular and chaotic state of the system dynamics which are verified with Lyapunov exponent and recurrence quantification analysis. The detailed analysis provides an understanding of multiple state transition in the dynamics of the system.
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