Nutrient Streams and the Subduction process: their effect on global nutrient distributions

生物生产导致有机物质从阳光照耀的海洋表面输出，这对于在海洋内转移碳和提供从大气中生物吸收二氧化碳非常重要。这种出口只有在向上层海洋有新的营养物质补偿供应的情况下才能持续几年。传统上，这种养分供应被解释为垂直平流或扩散转移。在这项提案中，我们转而探讨营养物质的水平转移如何维持表层营养物质的浓缩，从而维持出口生产。我们建议研究以下科学问题：1.边界流(通过营养流)和俯冲过程(混合层和温跃层之间的流体交换)如何控制海洋盆地的表层营养物质分布？2.模态水形成和扩散的年际变化如何影响副热带环流上层温跃层的营养库？3.微尺度涡旋如何维持上层温跃层内的营养物质浓度？这些问题是通过数据分析和耦合等压循环和氮模型实验相结合的方式解决的。

Biological production leads to an export of organic matter from the surface, sunlit ocean, which is important in transferring carbon within the ocean and in providing a biological drawdown of carbon dioxide from the atmosphere. This export can only be sustained over several years if there is a compensating supply of new nutrients to the upper ocean. Traditionally, this nutrient supply has been explained in terms of a vertical advective or diffusive transfer. In this proposal, we instead explore how the horizontal transfer of nutrients acts to maintain the surface nutrient concentrates and, thus, sustain export production. We propose to examine the following scientific questions: 1. How do boundary currents (through nutrient streams) and the subduction process (the exchange of fluid between the mixed layer and thermocline) control surface nutrient distributions over ocean basins? 2. How does interannual variability in mode water formation and spreading affect the nutrient reservoir of the upper thermocline for subtropical gyres? 3. How do fine-scale eddies sustain nutrient concentrations within the upper thermocline? These questions are addressed through a combination of data analyses and coupled isopycnic circulation and nitrogen model experiments.