Upwelling and Lateral Exchange Over the Patagonian Shelf and Impacts on Southern Ocean Primary Productivity

南大西洋拥有最大的叶绿素a水华--南大洋的水华，这可能与来自巴塔哥尼亚区域的场外流动有关。要对深海的生产力产生如此重大的影响，来自巴塔哥尼亚的离岸流量必须很大，并显示出很高的营养含量。该项目的总体目标是描述巴塔哥尼亚高生育率和高流量外流背后的物理过程。据推测，巴塔哥尼亚陆架流出的高营养物质部分是由一个从德雷克海峡延伸到巴西/马尔维纳斯交汇处的独特的陆架断裂上升流系统支撑的。这些假设将通过一系列嵌套的高分辨率模式模拟的分析来解决。这项研究与气候和海洋生态系统群落的研究有关。南大西洋西部环流、进入真光层的营养物质和铁的输入、大陆边缘排放和生物活动的任何变化，都将对自然二氧化碳的排出和人为二氧化碳的吸收的平衡产生重大影响。深入研究铁的输入及其对生态系统的调控，将进一步启发我们对这些地区未来二氧化碳通量变化的认识。此外，它将提供一些关于气候社区模型必须解决这些问题的过程和规模的一些见解。这项研究还可能有助于设计未来的实地活动，以解决尚未解决的南大洋太平洋和大西洋区段初级生产差异问题，以及观测将为这些问题提供答案的目标地点。研究生培训也将是这项研究的重要组成部分。假设这个高生产率系统由三个局部上升流中心组成：第一个中心沿着巴塔哥尼亚搁置带北部延伸，从48 S延伸到巴西/马尔维纳斯交汇处；第二个中心是伯德伍德浅滩，位于德雷克海峡北部的一个相对较浅的岸上；第三个中心是马尔维纳斯(福克兰)群岛。第二种假设是，来自巴塔哥尼亚的大量外流是由南极绕极流(ACC)和德雷克海峡北部海底地形之间的相互作用驱动的。为了解决这些假设，我们将分析几个面向过程的数值实验。这些实验以高分辨率嵌套模式配置为基础，还将允许调查次中尺度过程对区域环流的影响。关于巴塔哥尼亚异常断裂的水华及其与南大洋的大规模交换的物理机制的研究很少。事实上，以前没有关于伯德伍德浅滩和马尔维纳斯群岛上升流中心的研究，也很少有关于巴塔哥尼亚大陆架和南大洋之间的交换的研究。以前也没有关于次中尺度过程对西南大西洋环流影响的研究。然而，一项初步研究表明，这些过程影响着区域环流中重要而新颖的变化。该项目将要分析的数值实验是该地区最先进的。其中一些是这个团队之前研究工作的遗产，而另一些将在这个项目的过程中执行。

The South Atlantic sector hosts the largest chlorophyll-a blooms of the Southern Ocean, which are likely associated with off-shelf flows from the Patagonian region. To have such a significant impact on the productivity of the deep ocean the off-shelf flows from Patagonia must be large and exhibit a high nutrient content. The overall goal of this project is to characterize the physical processes underlying the high fertility and high volume transport of Patagonia's outflows. It is hypothesized that the high nutrient content of the Patagonia shelf outflows are partially sustained by a unique shelfbreak upwelling system extending from the Drake Passage to the Brazil/Malvinas Confluence. The hypotheses will be addressed with the analysis of a series of nested high resolution model simulations. This research is relevant to the climate and marine ecosystem community research. Any change in the circulation in the western South Atlantic, nutrient and iron input to the euphotic zone, continental margin discharge and biological activity will have a substantial effect on the balance of outgassing of natural carbon dioxide and uptake of anthropogenic carbon dioxide. A close study of the input of iron and its control on the ecosystem will further enlighten us on future changes of carbon dioxide fluxes in these regions. Furthermore, it will provide some insight on which processes and on which scale the climate community model will have to resolve them. The research may also help in the design of future field campaigns to address the unresolved questions of differences in primary production between the Pacific and Atlantic sectors of the Southern Ocean and target sites where observations will provide answers to these questions. Graduate training will also be an important component of this research.It is hypothesized that this highly productive system is composed of three localized upwelling centers: the first extending along the northern portion of the Patagonian shelfbreak, from 48 S to the Brazil/Malvinas Confluence; the second centered on the Burdwood Bank, a relatively shallow bank located in the northern portion of the Drake Passage; and the third centered on the Malvinas (Falkland) Islands. A second hypothesis is that the large off-shelf flows from Patagonia are driven by interactions between the Antarctic Circumpolar Current (ACC) and the bottom topography in the northern portion of the Drake Passage. To address these hypotheses, several process-oriented numerical experiments will be analyzed. These experiments, which are based on a high-resolution nested model configuration, will also allow an investigation of the impact of sub-mesoscale processes on the regional circulation. There are very few studies on the physical mechanisms sustaining Patagonia's extraordinary shelfbreak blooms and its mass exchanges with the Southern Ocean. In fact, there are no previous studies on the Burdwood Bank and the Malvinas Islands upwelling centers and very few on the exchanges between the Patagonian shelf and the Southern Ocean. There are also no previous studies on the impact of sub-mesoscale processes on the southwestern Atlantic circulation. A pilot study, however, shows that these processes influence important and novel changes within the regional circulation. The numerical experiments to be analyzed by this project are the state-of-the-art for this region. Some of them are the legacy of previous research efforts by this team, while others will be executed during the course of this program.