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

巴塔哥尼亚大陆架的上升流和横向交换及其对南大洋初级生产力的影响

• 批准号: 1559550
• 负责人: Ricardo Matano
• 金额: $ 44.78万
• 依托单位: Oregon State University
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2016
• 资助国家: 美国
• 起止时间: 2016-04-01 至 2020-03-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1559550&HistoricalAwards=false
• 关键词: Upwelling; Lateral; Exchange; Over; Patagonian

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.

南大西洋地区拥有南大洋中最大的叶绿素-a大量繁殖，这可能与来自巴塔哥尼亚地区的大陆架流动有关。要对深海的生产力产生如此重大的影响，来自巴塔哥尼亚的非大陆架流必须很大，并表现出高营养含量。该项目的总体目标是描述巴塔哥尼亚高生育率和大量流出的物理过程。据推测，巴塔哥尼亚陆架流出物的高营养成分部分是由一个独特的陆架断裂上升流系统维持的，该系统从德雷克海峡延伸到巴西/马尔维纳斯汇合处。这些假设将通过分析一系列嵌套的高分辨率模型模拟来解决。本研究与气候和海洋生态系统群落研究相关。南大西洋西部环流的任何变化、向光带输入的营养物质和铁、大陆边缘排放和生物活动都将对自然二氧化碳排放和人为二氧化碳吸收的平衡产生重大影响。对铁的输入及其对生态系统的控制的深入研究将进一步启发我们对这些地区未来二氧化碳通量的变化。此外，它还将提供一些见解，说明气候共同体模型必须以何种过程和规模来解决这些问题。这项研究还可能有助于设计未来的实地活动，以解决南大洋太平洋和大西洋部门之间初级生产差异的未解决问题，以及观察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。据推测，这一高产系统由三个局部的上升流中心组成：第一个上升流中心沿着巴塔哥尼亚大陆架断裂的北部延伸，从48 S到巴西/马尔维纳斯汇合处；第二次以伯德伍德海岸为中心，这是一个相对较浅的海岸，位于德雷克海峡的北部；第三个以马尔维纳斯（福克兰）群岛为中心。第二种假设是，来自巴塔哥尼亚的大量陆架流是由南极绕极流（ACC）和德雷克海峡北部底部地形之间的相互作用驱动的。为了解决这些假设，几个面向过程的数值实验将进行分析。这些实验以高分辨率嵌套模式配置为基础，也将有助于研究亚中尺度过程对区域环流的影响。关于维持巴塔哥尼亚非凡的冰架破裂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，以前没有对伯德伍德滩和马尔维纳斯群岛上升流中心的研究，对巴塔哥尼亚大陆架和南大洋之间的交流也很少有研究。亚中尺度过程对西南大西洋环流的影响也没有前人的研究。然而，一项初步研究表明，这些过程影响区域环流内重要的新变化。本项目所分析的数值实验是本地区最先进的。其中一些是这个团队以前研究工作的遗产，而其他的将在这个项目的过程中执行。