Collaborative Research: The Role of Wind in Estuarine Dynamics

智力优势：河口的物理作用取决于使其沃茨分层的力量和破坏这种分层的力量之间的竞争结果。60年来，人们一直认为潮汐是破坏性力量，它通过涨落在粗糙的海底产生湍流。近年来，一个新的玩家出现了：吹过河口的风。研究表明，风是一种有效的混合器，甚至可以达到使水柱分层的程度。最近，人们发现，这种混合发生，不仅作为一个一维的垂直过程，而且还通过应变的密度结构在纵向和横向的河口。该项目的驱动假设是，除了驱动强环流沿着和横跨河口，它也可以是一个主要的贡献者混合提供能量的经典两层河口环流，至少在河口与长fetches和较弱的流通。这个项目的目的是调查风在河口动力学中的作用，并验证这些假设。为了研究这一作用，河口的响应所施加的风应力必须在三维细节，尚未提供迄今为止的细节。此外，这种反应必须清楚地确定，从根本上的利益循环分开？更慢更宽的河口水流。最后，这种描述必须可扩展到更广泛的河口类。实现这一细节和理解需要一个广泛而深入的观察和分析计划，结合数值模型，有能力分离，解剖，整合和缩放的多个循环和混合组件。切萨皮克湾的观测计划将涉及一系列密集的仪器，其中最新颖的是一个高分辨率的塔，配有速度计和温度-盐度记录仪，可以直接测量应力分布。密集的浮标阵列将装有气象传感器，以测量风场中的局部结构。最后，一个多船，拖曳车采样计划的设计，以提供详细的空间图片的密度结构与足够高的重复率，以解决在潮汐周期的变化。与负责切萨皮克湾地区天气预报的气象学家建立伙伴关系，将有助于对这一复杂的互动系统进行观测和分析。更广泛的影响：河口的环流和封闭性质使其成为高产渔业，渔业受到人类改变景观的影响的威胁。世界各地的河口处于不同的退化状态，其主要原因是农业径流和城市污水带来的过量营养物质。这些营养物质使沃茨过度富集，导致下层的氧气下降，这种下降剥夺了生物资源利用这一宝贵栖息地的能力。在切萨皮克湾和长岛湾等河口，这些凹陷会导致缺氧甚至缺氧，溶解氧完全耗尽。昂贵的计划正在计划和进行中，以恢复我们国家的河口的健康。这些管理计划将需要依赖于一个准确的描述河口环流的物理，如果他们是成功的。此外，如果公众要提供必要的政治和经济支持，就需要了解问题和为解决问题所做的努力。为此，该研究项目将与教育和推广工作，特别是与COSEE沿海趋势计划和霍恩点实验室科学家教育家计划，并将涉及一名科学家教育家，他将领导一个本科生团队开发一个教学模块，该模块与河口环流（包括风混合）在切萨皮克湾死区中的作用有关。最后，本提案将为两名攻读博士学位的研究生和一名博士后研究员提供培训。

Intellectual Merit: The physical workings of an estuary depend on the outcome of a contest between forces acting to stratify its waters, and forces acting to destroy this stratification. For six decades, the destructive force has been identified as the tides, which generate turbulence through ebb and flow over the rough bottom. In recent years, a new player has emerged: wind blowing over the estuary. Research has shown wind to be an effective mixer, even to the point of de-stratifying the water column. More recently, it has been found that this mixing takes place, not solely as a one-dimensional vertical process, but also through straining of the density structure in the longitudinal and lateral direction of the estuary. The driving hypothesis for this project is that, in addition to driving strong circulations along and across the estuary, it can also be a major contributor to the mixing providing the energy for the classical two-layer estuarine circulation, at least in estuaries with long fetches and weaker circulation. This project has been designed to investigate the role of wind in estuarine dynamics and to test these hypotheses. In order to examine this role, the response of the estuary to an applied wind stress must be described in three-dimensional detail, detail that has not been provided heretofore. In addition, this response must be clearly identified, separate from the underlying circulation of interest?the slower, steadier estuarine flow. Finally, this description must be scalable to the broad class of estuaries. Achieving this detail and understanding requires an extensive and intensive program of observation and analysis in combination with numerical models that have the ability to separate, dissect, integrate, and scale the multiple circulation and mixing components. The observational program in the Chesapeake Bay will involve an intensive array of instrumentation, the most novel of which is a high-resolution tower equipped with velocimeters and temperature-salinity recorders that will enable direct measurements of the stress profile. A dense array of buoys will be instrumented with meteorological sensors to measure local structure in the wind field. Finally, a scheme of multi-ship, towed-vehicle sampling is designed to provide detailed spatial pictures of the density structure with a sufficiently high repetition rate to resolve changes over a tidal cycle. A partnership with the meteorologists responsible for weather forecasting in the Chesapeake Bay region will aid both the observation and analysis of this complex, interactive system.Broader Impacts: The circulation and enclosed nature of estuaries make them highly productive fisheries, fisheries threatened by the effects of human alteration of the landscape. Estuaries worldwide are in various states of degradation, the chief cause of which is excess nutrients delivered from agricultural runoff and municipal sewage. These nutrients over-enrich the waters and lead to oxygen sags in the lower layers, sags that deprive living resources of the ability to use this valuable habitat. In estuaries such as Chesapeake Bay and Long Island Sound, these sags can proceed to hypoxia and even anoxia, the total depletion of dissolved oxygen. Costly programs are planned and underway to restore the health of our nation's estuaries. These management programs will need to rely on an accurate description of the physics of estuarine circulation if they are to be successful. In addition, the public will need to be informed of both the problem and the efforts toward solutions if they are to provide the political and economic support necessary. To that end, this research project will engage with education and outreach efforts, especially with the COSEE Coastal Trends program and with the Horn Point Laboratory Scientist-Educator Program, and will involve a scientist-educator, who will head a team of undergraduates to develop a teaching module related to the role of estuarine circulation (including wind mixing) in the Chesapeake Bay's Dead Zone. Finally, this proposal will provide training to two graduate students pursuing PhD degrees and a Postdoctoral fellow.