2026-02-19 東北大学
図1. 2025年1月21日（左）と2月4日（右）の21時（日本時間）における気象衛星ひまわり8号の雲画像（千葉大学環境リモートセンシング研究センターの公開データを用いて作成）。インドネシア島嶼部を覆う巨大な雲の群れがMJOに伴うもの。この2週間の間に雲の群れの中心は東に移動しており、この群れから渦巻いた熱帯低気圧が発生している。
＜関連情報＞
- https://www.tohoku.ac.jp/japanese/2026/02/press20260219-01-MJO.html
- https://www.tohoku.ac.jp/japanese/newimg/pressimg/tohokuuniv-press20260219_01web_MJO.pdf
- https://www.science.org/doi/10.1126/sciadv.adz1916
決定論的カオス現象としてのマッデン・ジュリアン振動の伝播 Propagation of the Madden-Julian oscillation as a deterministic chaotic phenomenon
Daisuke Takasuka, Tamaki Suematsu, Hiroaki Miura, and Masuo Nakano
Science Advances Published:18 Feb 2026
DOI:https://doi.org/10.1126/sciadv.adz1916
Abstract
The Madden-Julian oscillation (MJO) is a planetary-scale tropical weather disturbance marked by eastward-propagating cumulus cloud clusters over the Indo-Pacific region, causing severe weather and climate events worldwide. The mechanism and predictability of MJO propagation remain elusive, partly because relevant multiscale processes are poorly understood. Here, we reveal chaotic MJO propagation arising from cross-scale nonlinear interactions, based on 4000-member ensemble simulations of two MJO events with a global cloud-system–resolving model. Against conventional linear thinking, multiple regimes with distinct timings of MJO propagation emerge under a single atmosphere-ocean background. The emergence of regime bifurcation 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 results contribute to a more complete MJO conceptual model and help foresee when coherent MJO propagation emerges.
