Small-scale turbulent mixing drives the upwelling of deep water masses in the abyssal ocean as part of the global overturning circulation¹. However, the processes leading to mixing and the pathways through which this upwelling occurs remain insufficiently understood. Recent observational and theoretical work^2,3,4,5 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 100 metres 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^3,6,7,8. The upwelling rates observed were approximately 10,000 times higher than the global average value required for approximately 30 × 10⁶ m³ s⁻¹ of net upwelling globally⁹.

作为全球翻转环流的一部分，小规模的湍流混合驱动深海深水团的上涌¹ 。然而，导致混合的过程以及这种上升流发生的途径仍然没有得到充分的了解。最近的观测和理论工作^{2、3、4、5}表明，深水上升流可能沿着海洋倾斜的海底发生；然而，迄今为止，证据都是间接的。在这里，我们展示了以每天 100 米量级的速度穿过等密度线的剧烈近底部上升流，以及近边界和内部流体的绝热交换。这些观测是使用在倾斜的海底峡谷内靠近海底释放的染料进行的，它们提供了深海中强烈的、集中于底部的双锥上升流的直接证据。这支持了之前的建议，即峡谷等地形特征的混合会导致全球显着的上升流^3,6,7,8 。观测到的上升流速率比全球净上升流约 30 × 10 ⁶ m ³ s ^-1所需的全球平均值高出约 10,000 倍⁹ 。