海氷の老化過程を拡散的脱塩で解明(Tsinghua researchers reveal the aging dynamics of sea ice driven by diffusive desalination)

2025-09-21 清華大学

清華大学の孫超教授率いる研究チームは、海氷の老化が「拡散的脱塩」によって支配されることを実証した。研究では、実験、理論モデル、数値シミュレーションを組み合わせ、塩水の凍結から20日間にわたる氷の変化を観察。初期の急速な凍結後、氷は徐々に空隙率が減少し、熱平衡下での温度差が塩分濃度勾配を生み出し、塩分が氷外に拡散することで純粋で緻密な氷へと変化することが確認された。この成果は、熱・物質移動や相変化を含む複雑な物理過程の理解を深め、海氷モデルや気候予測の精度向上に貢献するとされる。研究成果は『Physical Review Letters』に掲載され、Editors’ Suggestionに選ばれた。

海氷の老化過程を拡散的脱塩で解明(Tsinghua researchers reveal the aging dynamics of sea ice driven by diffusive desalination)
Fig 1: Newly-formed porous ice in salty water gradually ages into dense ice.

<関連情報>

拡散駆動型脱塩作用による海氷の老化 Sea Ice Aging by Diffusion-Driven Desalination

Yihong Du, Feng Wang, Enrico Calzavarini, and Chao Sun
Physical Review Letters
DOI: https://doi.org/10.1103/mct1-6hbw

Abstract

Sea ice is a key component of Earth’s climate system, making its aging process an essential focus of current research. The age of sea ice is closely linked to its thermal and mechanical properties, which govern its interactions with the surrounding environment. In this study, we combine experimental techniques and modeling to explore the full dynamical process of mushy ice growth and spontaneous aging in saline water, within a natural convective flow system. We show that the aging of newly formed mushy ice in the present system, characterized by a gradual long-term reduction in porosity, is controlled by diffusion-driven desalination. Moreover, we observe that the system eventually transits into a dense freshwater ice layer adjacent to a well-mixed saline water region. The shape of the ice layer in this asymptotic state is well captured by numerical simulations of nonporous ice. Our findings improve the understanding of the complex physics governing phase changes in aqueous systems and provide a framework for studying sea ice aging in laboratory settings, with implications spanning diverse natural and industrial applications.

0106流体工学
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