Capturing Oceanic Submesoscales, Stirring, and Mixing with Sound and Simulations

全球海洋就像一块海绵，吸收了大量因人类活动而添加到大气中的过剩热量和碳。因此，我们的海洋在缓冲气候变化的严重程度方面发挥着关键作用。然而，海绵未来的存储能力以及营养物质和氧气的分布是不确定的，而营养物质和氧气是健康海洋生态系统的关键成分。为了解决这些不确定性，我们需要更好地了解海洋如何在表层深处流动--特别是横跨数十米至数百公里尺度的洋流，也称为次中尺度。亚中尺度洋流之所以重要，是因为它们提供了一条利用风和潮汐能量的途径，并利用它来搅动和混合全球各地的不同水团，以及它们携带的热量、碳和营养物质。尽管它们很重要，但由于海洋亚中尺度的中等大小和间歇性，人们对它们知之甚少。这意味着它们在自然界中都很难捕捉，也很难用计算机建模。在这个项目中，我的团队将进行一项开创性的实验，首次捕捉到存在于表层海洋下面的各种洋流，以及它们所产生的混合和搅拌。使用主动声学的有针对性的出海方案将以前所未有的分辨率(比其他技术好两个数量级)对海洋进行采样，并充分捕获亚中尺度洋流。与蝙蝠的回声定位类似，水面上的船只向水中释放声音脉冲，并记录水层的反射。声学测量将首次与尖端机器人、船载和系泊仪器相结合。同时，最先进的模型模拟将使用我们新的海洋观测数据进行验证和改进。结果将是迄今为止最逼真的次表面海洋表示。这些模拟将用于量化次中尺度的启动、普遍存在和相互作用，并评估它们在推动全球海洋能量和性质交换方面的作用。这项实验将在全球海洋活动的热点地区进行：阿根廷海岸外的巴西-马尔维纳斯交汇处。在这里，来自大西洋的亚热带水域与来自南大洋的极地水域相撞。这一交汇处的水团交换很可能是由次中尺度流驱动的，在全球海洋中热量、盐、碳和维持生命的营养物质和氧气的分布中发挥着关键作用。通过在巴西-马尔维纳斯交汇处以无与伦比的细节揭示海洋内部的动力学，COSSMoSS将揭示科学海洋谜题中缺失的一个重要部分，帮助我们更好地了解我们未来的生物圈和气候。

The global oceans act as a sponge, soaking up significant amounts of the excess heat and carbon that have been added to the atmosphere due to human activity. Our oceans therefore play a key role in buffering the magnitude of climate change. However, the future storage capacity of the ocean sponge is uncertain, alongside the distribution of nutrients and oxygen, key ingredients for a healthy marine ecosystem. To address these uncertainties, we need to better understand how the oceans flow deep below the surface layers - in particular current flows that span scales of tens of metres to hundreds of kilometers, otherwise known as submesoscales. Submesoscale currents matter because they provide a pathway to harness energy from the winds and tides and use it to stir and mix different water masses around the globe, along with the heat, carbon and nutrients that they carry. Despite their importance, little is known about ocean submesoscales because of their intermediate size and intermittent nature. This means they are both difficult to capture in nature or model with computers. In this project, my team will conduct a pioneering experiment that will capture for the first time the full range of current flows that exist beneath the surface ocean layers, alongside the mixing and stirring that they generate. A targeted sea-going programme using active acoustics will sample the ocean at unprecedented resolutions (two orders of magnitude better than other techniques) and fully capture submesoscale currents. Similar to how bats echo-locate, a ship at the surface releases sound pulses into the water and records reflections from water layers. Acoustic measurements will be combined for the first time with cutting-edge robotics, vessel-mounted and moored instrumentation. In parallel, state-of-the-art model simulations will be both validated and improved using our new ocean observation data. The result will be the most realistic representation of the sub-surface ocean to date. The simulations will be used to quantify submesoscale initiation, ubiquity and interactions, and assess their role in driving energy and property exchanges in the global ocean. The experiment will take place at a global hotspot of ocean activity: the Brazil-Malvinas Confluence off the coast of Argentina. Here sub-tropical waters from the Atlantic collide with polar waters from the Southern Ocean. Water mass exchanges at this confluence, which are likely driven by submesoscale currents, play a key role in the distribution of heat, salt, carbon and life sustaining nutrients and oxygen throughout the global oceans. By revealing interior ocean dynamics in unparalleled detail at the Brazil-Malvinas Confluence, COSSMoSS will shed light on a significant missing piece of the scientific ocean puzzle helping us to better understand our future biosphere and climate.