美国加州大学圣地亚哥分校Wynne-Cattanach, Bethan L课题组取得一项新突破。他们报道了倾斜海底峡谷内底旋上升流的观测。相关论文于2024年6月26日发表在《自然》杂志上。

据研究人员介绍，小规模的湍流混合驱动深海深水团的上升流是全球翻转环流的一部分。然而，人们仍然没有充分的了解对导致混合的过程和这种上升流发生的途径。最近的观测和理论工作表明，深海上升流可能沿着海洋倾斜的海底发生。然而，到目前为止，还没有直接的证据能证明该结论。

研究人员展示了等密度线上强烈的近底上升流与近边界和内部流体的绝热交换，穿过速率为每天100m。这些观测是在一个倾斜的海底峡谷内靠近海底释放的着色剂中进行的，它们为深海中强烈的、以底部为中心的深海上升流提供了直接证据。该证据支持了先前的观点，即地形特征(如峡谷)的混合会导致全球显著的上升流。观测到的上升流速率比大约30×10⁶m³s^-1的全球净上升流的所需的，全球平均值高约10000倍。

附：英文原文

Title: Observations of diapycnal upwelling within a sloping submarine canyon

Author: Wynne-Cattanach, Bethan L., Couto, Nicole, Drake, Henri F., Ferrari, Raffaele, Le Boyer, Arnaud, Mercier, Herl, Messias, Marie-Jos, Ruan, Xiaozhou, Spingys, Carl P., van Haren, Hans, Voet, Gunnar, Polzin, Kurt, Naveira Garabato, Alberto C., Alford, Matthew H.

Issue&Volume: 2024-06-26

Abstract: Small-scale turbulent mixing drives the upwelling of deep water masses in the abyssal ocean as part of the global overturning circulation. However, the processes leading to mixing and the pathways through which this upwelling occurs remain insufficiently understood. Recent observational and theoretical work has suggested that deep-water upwelling may occur along the ocean’s sloping seafloor; however, evidence has, so far, been indirect. Here we show vigorous near-bottom upwelling across isopycnals at a rate of the order of 100metres per day, coupled with adiabatic exchange of near-boundary and interior fluid. These observations were made using a dye released close to the seafloor within a sloping submarine canyon, and they provide direct evidence of strong, bottom-focused diapycnal upwelling in the deep ocean. This supports previous suggestions that mixing at topographic features, such as canyons, leads to globally significant upwelling. The upwelling rates observed were approximately 10,000 times higher than the global average value required for approximately 30 × 10⁶m³s^-1 of net upwelling globally.

DOI: 10.1038/s41586-024-07411-2

Source: https://www.nature.com/articles/s41586-024-07411-2