A Numerical Study of the Patagonia Upwelling Region

巴塔哥尼亚陆架是一个宽阔的海底阶地，从拉普拉塔河(南纬36度)延伸到火地岛(南纬55度)。卫星和现场观测表明，该地区是一个活跃的上升流中心，拥有世界海洋中一些最大的叶绿素水华，其中最独特的是位于搁浅带。巴塔哥尼亚的搁置断裂上升流将铁和其他营养物质从南大洋的深层带到光层，不仅使大陆架水域肥沃，而且使南大西洋的整个亚极部分肥沃。例如，卫星观测显示，叶绿素羽流从南美洲延伸到澳大利亚。然而，尽管它对区域和半球有影响，但我们对巴塔哥尼亚的上升流及其与深海环流的相互作用知之甚少，这是本项目打算解决的问题。这是一项模拟研究，旨在研究巴塔哥尼亚陆架断裂上升流的动力机制以及陆架与深海之间的相互作用。基本前提是陆架断裂上升流主要受陆架底部地形的变化和马尔维纳斯海流输送的时间变化所调制。这项研究试图量化上升流的空间和时间变化，并将其与大气强迫联系起来。据推测，虽然当地风对上升流的影响很小，但大范围的风变化，特别是太平洋和印度盆地的风变化，可能会显著影响它的变异性。这项研究还将确定巴塔哥尼亚拥有最大跨架交易所的地区，并确定控制这些交易所的动力机制。预计巴塔哥尼亚在50-46年代之间通过勒梅尔海峡和陆架断裂区域进入亚南极水域，并主要在副热带陆架前沿卸货。广泛影响本研究将有助于正在进行的和未来的西南大西洋区域生物和地球化学项目的发展。例如，该项目将制定的上升流指数将有助于将观察到的巴塔哥尼亚生态系统的变化与搁浅上升流的大小变化以及气候变化的大范围模式联系起来。跨陆架交换机制(和区域)的确定将有助于我们理解碳循环和发展未来的观测计划。作为该项目的一部分，拟议的多学科讲习班将促进国际合作。该项目包括对一名博士生的支持，该博士生在整个研究过程中将与拉丁美洲的海洋学家密切合作。这一战略应该有助于促进对大陆架动力学感兴趣的下一代科学家的南北一体化。智力价值该项目建议在其最基本的层面上，测试关于在气旋西部边界流所包围的地区产生陆架破裂上升流和控制跨陆架交换的动力机制的新想法。这些论点足够普遍，适用于其他类似地区(例如新西兰、日本、威德尔海等)，从而扩大了该项目开发的智力工作的潜在影响。

The Patagonia shelf is a broad submarine terrace that extends from the mouth of the La Plata River (~36S) to the tip of Tierra del Fuego (~55S). Satellite and in-situ observations indicate that this region is an active upwelling center harboring some of the largest chlorophyll blooms of the world ocean, the most distinctive of which is located at the shelfbreak. Patagonia's shelfbreak upwelling brings iron and other nutrient from the deep layers of the Southern Ocean to the photic zone, fertilizing not only the shelf waters, but also the entire subpolar portion of the South Atlantic. Satellite observations, for example, show chlorophyll plumes extending from South America to Australia. Yet, in spite of its regional and hemispheric impact, we know little about Patagonia's upwelling regime or its interaction with the deep-ocean circulation, which this project intends to address. This is a modeling study to investigate the dynamical mechanisms driving Patagonia's shelfbreak upwelling and the interactions between the shelf and the deep ocean. The basic premise is that the shelfbreak upwelling is primarily modulated by the along-shelf variations of the bottom topography and time variations of the Malvinas Current transport. The study seeks to quantify the spatial and temporal variability of the upwelling and link it to the atmospheric forcing. It is hypothesized that, although local wind might have little impact over the upwelling, large-scale wind variations, particularly those over the Pacific and Indian basins might significantly influence its variability. The study will also identify the regions of Patagonia with the largest cross-shelf exchanges and identify the dynamical mechanisms controlling these exchanges. It is anticipated that Patagonia entrains Subantarctic waters through the Le Maire Straits and the shelfbreak region between ~50S and 46S, and primarily detrains at the Subtropical Shelf Front.Broader ImpactsThis study will contribute to the development to ongoing and future biological and geochemical projects of the southwestern Atlantic region. For example, the upwelling index that will be developed by this project will help to relate observed changes in the Patagonia's ecosystems to variations in the magnitude of the shelfbreak upwelling and to large-scale modes of climate variability. The identification of cross-shelf exchanges mechanisms (and regions) will contribute to our understanding of carbon cycles and the development of future observational programs. The multi-disciplinary workshop proposed as part of this project will foster international cooperation. The project includes support for a PhD student who, throughout her/his studies, will work in close collaboration with oceanographers in Latin America. This strategy should help to foster the north-south integration of the next generation of scientists interested in shelf dynamics.Intellectual MeritAt its most basic level this project proposes to test new ideas about the dynamical mechanisms generating shelfbreak upwelling and controlling cross-shelf exchanges in regions bounded by cyclonic western boundary currents. The arguments are general enough to be applicable to other similar regions (e.g., New Zealand, Japan, the Weddell Sea, etc), thus broadening the potential impact of the intellectual work developed in this project.