导  读 // Introduction

全球海平面上升正在对人类生存环境造成越来越大的威胁。如果南极冰盖全部融化，全球海平面将会上升近60米。因此，南极冰盖未来如何变化已成为全球变化研究领域最大的科学问题之一。由于南极地处遥远且自然环境恶劣，观测资料严重不足，影响南极冰盖融化的过程尚不清楚，未来全球海平面预测存在很大的不确定性，这为人类适应气候变化带来巨大的挑战。南极冰盖周边的冰架与海洋接触，导致冰架底部融化，随后产生冰架崩裂，这些过程是南极冰盖质量丢失的主要原因，也是目前国际关注的焦点。本文主要关注这方面近10年的主要进展，相关研究成果于2023年5月9日发表在Science合作期刊Ocean-Land-Atmosphere Research上。

主要内容 // Main Text

南极冰盖漂浮在海洋上的部分被称为冰架，冰架融化退缩将会促进冰盖向海洋的流动，引起海平面上升。多种尺度海洋过程如何影响冰架底部融化是本文关注的焦点。

图1  海洋过程向冰架底部输送热量示意图

图1展示了多种海洋过程引起的向冰架底部的热量输送过程。绕极深层暖水（CDW）跨越陆坡向陆架输送热量，陆架海洋过程继续向冰架前缘输送热量，穿越冰架前缘向冰腔内输送热量，冰腔内环流最终影响了热量向冰架底部的热量输送。这些海洋过程决定了冰架底部融化和冻结的分布形态。

绕极深层暖水受南极绕极流和亚极地环流的影响，在西南极附近和合作海（60-90°E）及其以东海域（大约至160°E）最靠近南极大陆，这两个区域的冰架因此最易出现融化退缩现象。涡旋和地形槽显著影响绕极深层暖水向陆架和冰架前缘的入侵。冰架前缘的立面对正压流有阻挡作用，也可以激发地形罗斯贝波，影响热量向冰腔内部的输送。冰腔内向冰架底部的热量输送受冰腔形状、冰腔内环流和水团分布的影响。由于直接观测严重不足，现代气候模式对这些海洋过程的模拟存在很大误差，导致未来气候和海平面预测存在很大的不确定性。

总结与展望

为了提高对未来气候和海平面变化预测的可靠性，未来应努力在以下几个方面加强研究：首先需要提高海底地形和冰架几何形状的观测精度，提高地形对海洋环流影响的模拟精度；其次需要加强对海洋中小尺度过程的观测和模拟研究，提高对向冰架底部的海洋热输送过程的模拟精度；然后需要加强研究南极冰盖质量变化对大气、海洋和海冰环流的反馈作用，实现大气、海洋、海冰、冰架和冰盖的全过程动态耦合模拟；加强观测与模拟相结合，加强多种类型和多种分辨率模式相互补充的模拟研究，将十分有利于提高对未来气候和海平面变化预测的可靠性。

扫码阅读原文，原文链接：https://doi.org/10.34133/olar.0010 

文章标题：

On the Multiscale Oceanic Heat Transports Toward the Bases of the Antarctic Ice Shelves

文章作者：

Zhaomin Wang, Chengyan Liu, Chen Cheng, Qing Qin, Liangjun Yan, Jiangchao Qian, Chong Sun and Li Zhang

文章摘要：

The mass balance of the Antarctic Ice Sheet (AIS) is important to global sea-level change. The AIS loses mass mainly through basal melting and subsequent calving of the Antarctic ice shelves. However, the simulated basal melting rates are very uncertain in ice sheet models, partially resulting from the poor understanding of oceanic heat transports. In this article, we review the recent progress in understanding and simulating such heat transports. Regulated by major circulation features, Circumpolar Deep Water (CDW) is much closer to the Bellingshausen–Amundsen Seas and the Cooperation Sea (60°E to 90°E) and the sector further east to 160°E. The ice shelves within these sectors are experiencing enhanced basal melting resulting from tropical forcing and intensified westerlies. Around West Antarctica, the isopycnal structure favors the delivery of CDW across slopes and shelves, while around East Antarctica, the persistent and strong westward Antarctic Slope Current (Front) acts to prevent warm-water intrusion. Both eddies and troughs favor heat transport to the fronts of the ice shelves and even into the cavities. The sharp contrast between the water column thicknesses on both sides of ice shelf fronts blocks the barotropic inflows and can excite topographic Rossby waves. Inside the cavities, the heat fluxes to the bases of the ice shelves are controlled by the cavity geometry, the circulations in the cavities, and the properties of the water masses beneath the ice shelves. Limited direct observations of cavities have promoted the development of various models. To improve basal melting simulations, meltwater plume models have been developed to study meltwater-laden mixed layer dynamics by increasing the vertical resolution, with recent advanced studies considering the vertical structures of frazil ice concentration and velocity. To reduce the uncertainties in the simulated and projected basal mass loss of the Antarctic ice shelves, future efforts should be devoted to improving the bathymetry and cavity geometry, investigating small-scale processes and parameterizing these processes in coupled climate–ice sheet models, and quantifying the feedback from the mass loss of the AIS.

文章引用：

Wang Z, Liu C, Cheng C, Qin Q, Yan L, Qian J, Sun C, Zhang L. On the Multiscale Oceanic Heat Transports Toward the Bases of the Antarctic Ice Shelves. Ocean-Land-Atmos. Res. 2023;2:Article 0010. 

https://doi.org/10.34133/olar.0010

OLAR简介

Ocean-Land-Atmosphere Research (OLAR)由南方海洋实验室和美国科学促进会合作出版，入选2022年度中国科技期刊卓越行动计划高起点新刊项目。期刊以“服务科学研究，推动技术创新”为办刊宗旨，坚持发表高质量、高水平论文，力争成为具有较大影响力的国际一流学术期刊。本刊以海洋相关学科为重点，刊稿主题包括但不限于：海陆气相互作用、海洋碳中和、物理海洋学、海洋生物与生态、海洋地质与地球物理、化学海洋学、海洋气象学、大气物理与大气环境、冰冻圈科学、河口海岸学、海洋工程与海洋技术、海洋资源开发与利用。OLAR投稿系统目前已正式开放，热烈欢迎相关研究领域科学家踊跃投稿。分享卓见，探索前沿，OLAR诚邀您一起荟萃科学发现，共享学术盛筵！