Hamiltonian properties of Madden-Julian Oscillation: waves and distributed chaos

TL;DR

This study analyzes the Madden-Julian Oscillation using spectral methods, revealing Hamiltonian distributed chaos characteristics and their potential influence on Asian-Australian Monsoons at intraseasonal scales.

Contribution

It introduces a Hamiltonian chaos framework to understand MJO dynamics and identifies a stretched exponential spectral decay in smoothed indices.

Findings

Spectral analysis shows a stretched exponential decay in MJO indices.

High-frequency noise is filtered out using a 3-day running average.

Hamiltonian distributed chaos impacts Asian-Australian Monsoon variability.

Abstract

The Madden-Julian Oscillation (MJO) has been studied using its daily RMM1, RMM2 and VPM1, VPM2 principal components' indices. A spectral analysis of the raw indices indicates presence of a noise presumably contributed by the random high-frequency waves. A soft simple filter - 3 day running average, has been applied to filter out this high-frequency noise (the filter has been chosen in accordance with the observationally known properties of these waves). Power spectrum of the smoothed indices exhibits a stretched exponential decay $E(f) \propto \exp-(f/f_0)^{1/2}$ characteristic to the Hamiltonian distributed chaos with spontaneously broken time translational symmetry (with time depending Hamiltonian and adiabatic invariance of the action). An impact of the MJO's Hamiltonian distributed chaos on the Asian-Australian Monsoons at the intraseasonal time scales has been briefly discussed.