A Stochastic Conceptual Model for the Coupled ENSO and MJO

TL;DR

This paper introduces a stochastic conceptual model that captures the complex interactions between ENSO and MJO, including their variability and extreme events, using a simplified three-box ocean model and Fourier atmospheric representation.

Contribution

The model uniquely combines a three-box ocean framework with a Fourier-based atmospheric component and incorporates decadal variability and state-dependent noise for improved simulation.

Findings

Successfully reproduces non-Gaussian statistics of ENSO and MJO spectra.

Captures the interactions between wind, ENSO, and MJO.

Models the influence of decadal variability on ENSO diversity.

Abstract

Understanding the interactions between the El Nino-Southern Oscillation (ENSO) and the Madden-Julian Oscillation (MJO) is essential to studying climate variabilities and predicting extreme weather events. Here, we develop a stochastic conceptual model for describing the coupled ENSO-MJO phenomenon. The model adopts a three-box representation of the interannual ocean component to characterize the ENSO diversity. For the intraseasonal atmospheric component, a low-order Fourier representation is used to describe the eastward propagation of the MJO. We incorporate decadal variability to account for modulations in the background state that influence the predominant types of El Nino events. In addition to dynamical coupling through wind forcing and latent heat, state-dependent noise is introduced to characterize the statistical interactions among these multiscale processes, improving the simulation of extreme events. The model successfully reproduces the observed non-Gaussian statistics of ENSO diversity and MJO spectra. It also captures the interactions between wind, MJO, and ENSO.