The ventilation of South Georgia's Deep Waters

该项目的目的是确定导致深层和海底沃茨卷入南格鲁吉亚岛（南大洋）表层的物理过程，并评估其对气候变化的敏感性。南格鲁吉亚（SG）是南大洋一些最大的叶绿素水华的发源地。观测表明，海洋环流驱动了这些水华，但受精过程背后的物理过程的性质尚不清楚。一个面向过程的模拟程序将寻求，一方面，以确定的来源和动力机制的基础上的SG区域的施肥，另一方面，以评估其对气候变率和气候变化的敏感性。该研究与气候和海洋生态系统群落研究相关，了解SG的施肥过程不仅有助于预测气候变化对区域生态系统的影响，而且有助于预测这些生态系统对气候变化的潜在反馈。SG环流的任何变化、真光层的营养物和铁输入、大陆边缘排放和生物活动将对天然CO2的释气和人为CO2吸收的平衡产生重大影响。此外，这项研究将提供一些关于气候群落模型必须解决哪些过程和规模的见解。这项研究还将有助于设计实地活动，以解决南大洋大西洋部分尚未解决的初级生产问题，并在观测结果将提供这些问题答案的目标地点进行。研究生培训将是研究的重要组成部分。目前对SG异常水华维持的物理机制，特别是其区域环流的研究很少。这是一个令人关切的问题，因为观测表明，南格鲁吉亚的水华是气候系统的一个重要组成部分，主要是由物理过程驱动的。例如，关于SG的大陆架环流的研究很少，几乎没有关于其与南大洋的物质交换的研究。然而，一项试点研究表明，大陆架过程及其与深海的相互作用对该区域的生物地球化学平衡至关重要。本项目所分析的数值试验是该地区的最新成果。据推测，SG的高生产力是基于大陆架和深海之间的有力的水交换和持续的，虽然仍然低估，沿海涌升系统。此外，它是假定SG施肥强烈依赖于风强迫和SO风的预期加强也将放大施肥过程，从而导致气候变化的负反馈。该奖项反映了NSF的法定使命，并已被认为是值得通过使用基金会的智力价值和更广泛的影响审查标准进行评估的支持。

This project aims to characterize the physical processes contributing to the entrainment of deep and benthic waters into the surface layers of the South Georgia Island (Southern Ocean) and to assess their sensitivity to climate variability. South Georgia (SG) hosts some of the largest chlorophyll blooms of the Southern Ocean. Observations suggest that the ocean circulation drives these blooms, but the nature of the physical processes underlying the fertilization process are unknown. A process-oriented modeling program will seek, on the one hand, to identify the sources and dynamical mechanisms underlying the fertilization of the SG region and, on the other hand, to evaluate their sensitivity to climate variability and climate change. The research is relevant to the climate and marine ecosystem community research.Understanding of SG's fertilization processes will not only contribute to the forecast of the impact of climate change on the regional ecosystems but also to anticipate the potential feedbacks that those ecosystems will have on the changing climate. Any change in the circulation in the SG, 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 CO2 and uptake of anthropogenic CO2. Furthermore, this study will provide some insight on which processes and on which scale the climate community model will have to resolve them. This research will also help in the design of field campaigns to address the unresolved questions of primary production in the Atlantic sector of the Southern Ocean and target sites where observations will provide answers to these questions. Graduate training will be an important component of the research.There are very few studies on the physical mechanisms sustaining SG's extraordinary blooms and, in particular, on its regional circulation. This is a matter of concern because observations suggest that South Georgia's blooms, which are an important component of the climate system, are primarily driven by physical processes. There are, for example, few studies on SG's shelf circulation and virtually none on its mass exchanges with the Southern Ocean. A pilot study, however, shows that shelf processes and its interaction with the deep ocean are critical to bio-geochemical balance of this region. The numerical experiments to be analyzed by this project are the state-of-the-art for this region. It is hypothesized that SG high productivity is based on vigorous water exchange between the shelf and the deep ocean and a persistent, albeit still under-appreciated, coastal upwelling system. Further, it is posited that SG fertilization is strongly dependent on wind forcing and the expected strengthening of the SO winds will also amplify the fertilization processes leading, therefore, to a negative feedback for climate change.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.