Ocean Circulation, Lateral Transfers of Nutrients, and the Air-Sea Flux of CO2

生物生产力由必需营养素的可用性调节。在海洋中，下沉的有机颗粒的输出无情地将营养物质输送到更深、更密集的海洋沃茨。 最终，物理运输必须将这些营养物质返回到可以发生光合作用的较轻的表面沃茨。然而，所观察到的跃层中的diapycnal混合率太小，无法平衡有机质的向下通量。 因此，一个显着的（也许占主导地位的）贡献，营养物质的diapycnal转移必须发生在表层海洋的横向运输。这是由海-气浮力通量促进的，并受剩余平均流的支配，剩余平均流在表层海洋中是横向埃克曼和涡流转移的净效应。在这项研究中，马萨诸塞州理工学院的研究人员将使用一系列模型，从简化的尺度参数到海洋环流和海洋地球化学循环的数值模型，以解决以下假设：1。表面剩余平均流支持横向，跨南极绕极流的营养物质的diapycnal传输和维持生产力的大西洋盆地在很长的时间尺度。在北大西洋的环流边界的类似过程有助于维持营养收支和副热带环流的生产力。2.南极绕极流和环流间边界附近的海气碳通量模式可以通过剩余平均流和等密度涡动搅拌的碳和营养物质输送来理解和预测。3.南大洋残余环流输送的营养物和碳在世纪和更长的时间尺度上对全球海洋碳泵和大气二氧化碳水平具有重大控制作用，并受到海气动量和浮力通量的气候变化的调节。 在这项研究的更广泛影响中，这项工作将导致麻省理工学院海洋环流和地球化学模型的继续发展。该模型是一个免费提供的工具，示踪剂和地球化学包的国际用户基础日益扩大。这项工作也有一个强大的培训组成部分，包括对研究生的支持。 此外，研究人员正在为研究生撰写一本关于海洋生物地球化学循环的跨学科书籍。

ABSTRACTOCE-0525974Biological productivity is regulated by the availability of essential nutrients. In the oceans, export of sinking organic particles inexorably transports nutrients towards the deep, denser ocean waters. Ultimately, physical transport must return those nutrients to the lighter, surface waters where photosynthesis can occur. However, observed diapycnal mixing rates in the thermocline are too small to balance the downward flux of organic matter. Therefore, a significant (perhaps dominant) contribution to the diapycnal transfer of nutrients must occur as lateral transport in the surface ocean. This is facilitated by air-sea buoyancy fluxes and governed by the residual mean flow, which in the surface ocean is the net effect of lateral Ekman and eddy transfers. In this research, researchers at the Massachusetts Institute of Technology will use a hierarchy of models, ranging from simplified scaling arguments to numerical models of ocean circulation and biogeochemical cycles, to address the following hypotheses: 1. The surface residual mean flow supports lateral, diapycnal transfers of nutrients across the Antarctic Circumpolar Current and sustains the productivity of the Atlantic Basin on long timescales. An analogous process at the inter-gyre boundary of the North Atlantic helps to sustain the nutrient budget and productivity of the subtropical gyre. 2. Patterns of air-sea carbon flux in the vicinity of the Antarctic Circumpolar Current and inter-gyre boundary can be understood and predicted in terms of the transport of carbon and nutrients by the residual mean flow and isopycnal eddy stirring. 3. The transport of nutrients and carbon by the residual circulation of the Southern Ocean has a significant control on the global ocean carbon pumps and atmospheric carbon dioxide levels on century and longer timescales, regulated by climatic changes in air-sea momentum and buoyancy fluxes. Among the broader impacts of the research, the work will lead to continued development of the MIT ocean circulation and biogeochemical model. The model is a freely available tool and there is a growing international user base for the tracer and biogeochemical packages. The work also has a strong training component that includes support for a graduate student. In addition, the investigators are engaged in writing an interdisciplinary book of ocean biogeochemical cycles for graduate students.