据悉，海洋中的湍流混合对翻转环流的速率和结构起着重要的控制作用。然而，支撑这种混合的过程的平衡受制于显著的不确定性，限制了人们对倾覆的深层上升流的理解。
研究研究了迄今为止主要被忽视的数十种海山在维持深海上升流中的作用。动力学理论表明，海山可以通过产生背风波和地形尾流涡来搅动和混合深水。在低纬度地区，预计尾流中的层状涡流会加强搅拌和混合。研究通过对赤道到中纬度的三个真实区域模拟表明，分层尾涡流和高混合在海山周围广泛存在。
研究确定了将海山尾流中混合率与地形和水文参数比例关系联系起来的标度。然后将这种尺度变换应用于全球海山数据集和海洋气候学，以表明海山产生的混合对深海上升流有重要贡献。该研究工作将海山带到了深海混合问题的前沿，并推动了在观测、理论和建模方面的工作，以将海底山的混合效应纳入概念和数值海洋环流模型。
附：英文原文
Title: On the role of seamounts in upwelling deep-ocean waters through turbulent mixing
Author: Mashayek, Ali, Gula, Jonathan, Baker, Lois E., Naveira Garabato, Alberto C., Cimoli, Laura, Riley, James J., de Lavergne, Casimir
Issue&Volume: 2024-6-25
Abstract: Turbulent mixing in the ocean exerts an important control on the rate and structure of the overturning circulation. However, the balance of processes underpinning this mixing is subject to significant uncertainties, limiting our understanding of the overturning’s deep upwelling limb. Here, we investigate the hitherto primarily neglected role of tens of thousands of seamounts in sustaining deep-ocean upwelling. Dynamical theory indicates that seamounts may stir and mix deep waters by generating lee waves and topographic wake vortices. At low latitudes, stirring and mixing are predicted to be enhanced by a layered vortex regime in the wakes. Using three realistic regional simulations spanning equatorial to middle latitudes, we show that layered wake vortices and elevated mixing are widespread around seamounts. We identify scalings that relate mixing rate within seamount wakes to topographic and hydrographic parameters. We then apply such scalings to a global seamount dataset and an ocean climatology to show that seamount-generated mixing makes an important contribution to the upwelling of deep waters. Our work thus brings seamounts to the fore of the deep-ocean mixing problem and urges observational, theoretical, and modeling efforts toward incorporating the seamounts’ mixing effects in conceptual and numerical ocean circulation models.
DOI: 10.1073/pnas.2322163121
Source: https://www.pnas.org/doi/abs/10.1073/pnas.2322163121