Physics Linking Shelf Circulation to Estuarine Inflow

我们将使用理论和理想化的数值实验来探索控制从沿海海洋流入河口或峡湾入海口的水源的物理问题。具体目标是发展对取水深度和取水地理区域的理论预测。这两个属性将被表示为控制环境变量的函数。参数空间将跨越各种各样的系统，从缓坡陆架上的浅海平原河口，到毗邻横跨陆架的峡谷的深峡湾。这项研究将告诉数值模型师，为了成功预测流入河口的水的性质，必须在陆架上包括什么物理因素。这将改进对河口生物地球化学功能变化的未来预测，这是由于沿海海洋中的水性质发生了变化。首席研究人员和一名研究生将把拟议研究的结果直接与他们所在地区的利益相关者联系起来，并将结果传达给致力于在其他地区取得预期社会结果的科学家。基于先前关于海岸上升流、峡谷、河流羽流和河口交换流动的广泛工作，已经存在部分理论框架。然而，陆架上流入的水流在到达河口之前的动态仍然相对未被探索，与收集的河流羽流相比，观测证据要少得多。两层流的早期解析解将是一个关键的起点。将进行理想化的数值实验，以检验假设的力平衡和这组解的流入路径。数值试验中的力平衡将使用三种方法进行分析：(I)沿流入粒子轨迹的拉格朗日动量收支，(Ii)倒退时间粒子跟踪，以有效地确定流入路径，以及(Iii)密度(盐度)类的平均，以区分纯平流输送和需要混合的输送。每种方法都有各自的优点和缺点，但结合起来应该为理论的发展提供明确的指导，特别是从两层到连续分层。在整个项目中，理论解释数值解的重要性质的能力将是成功的检验。

The physics controlling the source of waters flowing from the coastal ocean into the mouth of an estuary or fjord will be explored using theory and idealized numerical experiments. The specific goals are to develop theoretical predictions of the depth from which source water is drawn and the geographical region from which it is drawn. These two properties will be expressed as functions of controlling environmental variables. The parameter space will span a wide variety of systems, from shallow coastal plain estuaries on a gently sloping shelf, to deep fjords adjoining a shelf-crossing canyon. This research will inform numerical modelers about what physics must be included on the shelf in order to successfully predict the properties of water flowing into an estuary. This will allow improved future predictions of the change in estuarine biogeochemical function due to changing water properties in the coastal ocean. The principal investigator and a grad student will connect the results of the proposed research directly with stakeholders in their own region, and will communicate results to scientists working toward desired societal outcomes in other regions.Parts of a theoretical framework already exist, based on extensive previous work on coastal upwelling, canyons, river plumes, and the estuarine exchange flow. However the dynamics of the inflow on the shelf before it reaches the estuary remain relatively unexplored, with substantially less observational evidence than has been gathered for river plumes. Early analytical solutions for two-layer flow will be a key starting point. Idealized numerical experiments will be conducted to test the assumed force balance and inflow paths of this set of solutions. Force balances in the numerical experiments will be analyzed using three methods: (i) Lagrangian momentum budgets along inflow particle tracks, (ii) backward-in-time particle tracking to efficiently determine inflow pathways, and (iii) averaging in density (salinity) classes to separate purely advective transport from that requiring mixing. Each offers advantages and drawbacks, but in combination they should provide clear guidance for advancing the theory, particularly moving from two layers to continuous stratification. Throughout the project the ability of a theory to explain important properties of the numerical solutions will be the test of success.