「異常波」現象は通常の波の重なりで説明可能(Rogue Waves Aren’t Freaks of Nature ― They’re Just a ‘Bad Day’ at Sea)

2025-08-04 ジョージア工科大学

ジョージア工科大学の研究で、海上で発生する異常波(ローグウェーブ)は神秘的現象ではなく、通常の波の特性が重なって生じることが判明。北海で18年間・2万7500件の波データを解析した結果、①速度や方向の異なる波が重なり合う線形フォーカシング、②波の山を15~20%高くする第2次非線形効果、この二つが同時に起こることで極端に高い波が生じると分かった。理解が進めば異常波は説明可能な極端事象として扱え、NOAAや企業も海事リスク管理に応用を開始。機械学習による波高・方向・タイミングの解析で予測精度向上も期待される。

「異常波」現象は通常の波の重なりで説明可能(Rogue Waves Aren’t Freaks of Nature ― They’re Just a ‘Bad Day’ at Sea)
A size comparison of the “Draupner Wave” to 3 school buses stacked horizontally on top of one another.

<関連情報>

北欧の異常波における結合波非対称性の影響 Effects of bound-wave asymmetry on North Sea rogue waves

Sagi Knobler,Mika P. Malila,M. Aziz Tayfun,Dan Liberzon & Francesco Fedele
Scientific Reports  Published:DOI:https://doi.org/10.1038/s41598-025-07156-6

Abstract

Since the 1990s, modulational instability has been proposed as an alternative to the constructive interference of waves to explain the occurrence of rogue waves in the open ocean. This study questions the relevance of this instability for real rogue waves by analyzing a novel dataset of high-frequency laser altimeter wave measurements collected over an 18-year period (2003-2020) at the offshore Ekofisk platform in the central North Sea. A composite statistics of the ensemble of 27505 half-hourly sea states, accounting for data heterogeneity, show that third-order modulational instabilities do not significantly impact large waves; instead, second-order bound nonlinearities, shaping waves with asymmetric sharper crests and shallower troughs, are the primary factor that enhances the linear dispersive focusing, or constructive interference, of extreme waves.

0106流体工学
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