南極の氷床融解と海洋下層の“嵐”の関連を解明(UC Irvine researchers link Antarctic ice loss to ‘storms’ at the ocean’s subsurface)

2025-11-18 カリフォルニア大学アーバイン校(UCI)

University of California, Irvine(UCI)とJet Propulsion Laboratory(JPL)による研究チームは、南極の氷床融解に対して、海洋の“亜メソスケール”渦・渦巻きといった短期・小規模の海中「嵐」様循環が重要な役割を果たしていると明らかにした。語にすると、浮氷棚下面に暖水が亜メソスケール現象によって流れ込み、Thwaites GlacierやPine Island Glacierなど西南極アムンゼン海域の主要氷河で見られる急速な氷損失の約1/5の変動を、数時間以内に引き起こし得ることが示された。観測と高解像度シミュレーションから、この氷–海洋結合プロセスは融解が進むと渦が強まり、更なる暖水侵入を促す正のフィードバックループとして機能する。研究は、気象的時間スケールの海中運動が氷床安定性に与える影響を初めて定量化し、海レベル上昇予測や寒冷域モデルにおいてこれら未考慮の短時間・微細スケール過程を取り込む必要性を強調する。

<関連情報>

南極の氷空洞内の海底融解の要因としての海洋サブメソスケール Ocean submesoscales as drivers of submarine melting within Antarctic ice cavities

Mattia Poinelli,Lia Siegelman & Yoshihiro Nakayama
Nature Geoscience  Published:18 November 2025
DOI:https://doi.org/10.1038/s41561-025-01831-z

南極の氷床融解と海洋下層の“嵐”の関連を解明(UC Irvine researchers link Antarctic ice loss to ‘storms’ at the ocean’s subsurface)

Abstract

Thwaites and Pine Island glaciers—located in the Amundsen Sea Embayment, West Antarctica—are responsible for more than one-third of the total ice loss from Antarctica. These glaciers are experiencing accelerated retreat due to a combination of complex air–sea-ice processes. The ice cavities—the ocean-filled spaces beneath glaciers where the ice becomes afloat in the form of ice shelves—are particularly vulnerable to warm water intrusions but remain severely understudied due to their remote location and the lack of numerical models capable of resolving small-scale ice–ocean processes. Here we show that ocean submesoscale features (1–10 km size) regularly form in the open ocean, propagate towards Thwaites Glacier, intrude its cavity and melt the ice from below. We use an ice–ocean numerical model at 200-m resolution and observations below the ice to reveal that submesoscale motions are ubiquitous year round in the Amundsen Sea Embayment. Results show that submesoscales account for one-fifth of the total submarine melt variance in the area and highlight a positive feedback loop between submesoscale motions and submarine melting. Following this loop, as future climate warming implies greater ocean-induced melting, these events will become increasingly frequent, with far-reaching implications for ice-shelf stability and global sea-level rise.

1702地球物理及び地球化学
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