Exploring AMOC controls on the North Atlantic carbon sink using novel inverse and data-constrained models (EXPLANATIONS)

全球海洋目前吸收了人类活动释放到大气中的二氧化碳(CO2)的四分之一，减缓了气候变化的速度。不成比例的这种人为碳(CATH)积聚在北大西洋。全球海洋环流的一个组成部分大西洋子午线翻转环流(AMOC)在海洋碳吸收(碳汇)如何因物理、生物和化学之间的相互作用而变化方面发挥着关键作用。然而，该系统的模型模拟之间的分歧限制了人们对气候预测的信心。前工业化环境中已经存在的人为碳和“天然”碳对海洋碳净吸收的相对贡献也存在不确定性，以及这些贡献在未来可能如何变化。近年来，停泊在北大西洋的仪器首次在称为“RAPID”和“OSNAP”的方案中对大气环流进行了直接连续观测，提供了有关区域环流的新信息。此外，对海洋内部碳的观察使我们能够确定碳是如何在盆地中积累的。观测数据的可获得性和具有重要气候意义的区域环流相结合，使北大西洋成为研究控制海洋碳吸收、运输和储存的潜在机制的理想场所，有助于我们改进我们的模型。在这个项目中，我们将使用尖端方法来描述北大西洋二氧化碳汇和内部碳库。首先，我们将使用一种新的逆方法，该方法将观测与简单的物理原理相结合，使用不同的观测数据集的组合来估计碳的吸收、运输和储存，包括来自RAPH和OSNAP计划的数据集。其次，我们将使用一个模拟海洋物理、化学和生物系统的模型，同时以最大限度地提高模拟的真实性的方式纳入现有的观测，以探索北大西洋碳汇中环流的作用。我们将首次将OSNAP和快速观测纳入这个名为“ECCO-Darwin”的模型中，并将对该地区不断变化的碳清单的自然和人为贡献分开。第三，我们将使用最先进的海洋生态系统模型‘NEMO-PlankTOM’来估计海洋环流的快速变化对碳汇的影响，并确定碳汇与海洋生物生态系统之间的任何相互作用的强度。最后，我们将比较气候模型的输出与我们的结果，以确定这些模型中最能代表北大西洋碳吸收、运输和储存的共同特征，以此作为改进我们对未来气候变化预测的一种手段。总而言之，这些组合方法将更好地理解AMOC和北大西洋是如何封存人为二氧化碳的。

The global ocean currently absorbs a quarter of the carbon dioxide (CO2) released into the atmosphere due to human activities, slowing the rate of climate change. A disproportionate amount of this anthropogenic carbon (Canth) accumulates in the North Atlantic. A component of the global ocean circulation known as the Atlantic Meridional Overturning Circulation (AMOC) plays a key role in how the ocean carbon uptake (the carbon 'sink') varies due to interactions between physics, biology, and chemistry. However, disagreement among model simulations of the system limits confidence in climate projections. There is also uncertainty in the relative contributions to net ocean carbon uptake of anthropogenic carbon and 'natural' carbon that already existed in the preindustrial environment, and how these contributions may change in the future. In recent years, instruments moored in the North Atlantic have made the first direct continuous observations of the AMOC in programmes call 'RAPID' and 'OSNAP', providing new information about the regional circulation. Furthermore, observations of carbon in the ocean interior allow us to determine how carbon is accumulating in the basin. The combination of the availability of observational data and a climatically important regional circulation make the North Atlantic an ideal place to study the underlying mechanisms controlling ocean carbon uptake transport and storage, to help us improve our models.In this project, we will employ cutting-edge methods to characterise the North Atlantic Ocean CO2 sink and interior carbon reservoir. First, we will use a novel inverse method, which combines observations with simple physical principles, to estimate the uptake, transport, and storage of carbon, using a combination of different observational datasets, including those from the RAPID and OSNAP programmes. Second, we will use a model that simulates the ocean physical, chemical, and biological systems, while incorporating available observations in a way that maximises the realism of the simulation, to explore the role of the circulation in the North Atlantic carbon sink. For the first time, we will incorporate OSNAP and RAPID observations into this model, named 'ECCO-Darwin', and separate natural and anthropogenic contributions to the region's changing carbon inventory. Third, we will use the state-of-the-art ocean ecosystem model 'NEMO-PlankTOM' to estimate the impacts of rapid changes in the ocean circulation on the carbon sink, and to determine the strength of any interaction between the carbon sink and the ocean's biological ecosystem. Finally, we will compare outputs from climate models with our results to identify common features in those models that best represent North Atlantic carbon uptake, transport, and storage, as a means of improving our projections of future climate change. In summary, these combined methods will provide an improved understanding of how the AMOC and North Atlantic Ocean are sequestering anthropogenic CO2.