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arXiv · 2506.23195

Propagation of the Madden-Julian oscillation as a deterministic chaotic phenomenon

Daisuke Takasuka·Tamaki Suematsu·Hiroaki Miura·Masuo Nakano
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Abstract

The Madden-Julian oscillation (MJO), a gigantic tropical weather system, is marked by eastward travel of cumulus cloud clusters over the Indo-Pacific region and often causes severe weather and climate events worldwide. The physics and predictability of MJO propagation remain elusive, partly because of little attention to untangling roles of multi-scale processes relevant to the MJO. Here, we reveal the chaotic nature of MJO propagation arising from cross-scale nonlinear interactions, based on 4,000-member ensemble global cloud-system-resolving simulations of two MJO events. Against conventional linearized thinking, multiple regimes with distinct timings of MJO propagation emerge under a single atmosphere-ocean background. The bifurcation emergence depends critically on the equatorial asymmetry of climatological sea surface temperature. Selection of the bifurcated regimes is probabilistic, influenced by whether tropical-extratropical interplay promotes moistening associated with westward-propagating tropical waves over the western Pacific. These aspects help build a comprehensive MJO model and foresee when the MJO propagates.

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Daisuke Takasuka, Tamaki Suematsu, Hiroaki Miura, Masuo Nakano. 2025-06-29. Propagation of the Madden-Julian oscillation as a deterministic chaotic phenomenon. https://arxiv.org/abs/2506.23195

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