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Collaborative Research: Lagrangian transport and patchiness of buoyant material in estuarine systems

合作研究：河口系统中浮力物质的拉格朗日输送和斑块性

基本信息

批准号：
2148375
负责人：
Robert Chant
金额：
$ 29.23万
依托单位：
Rutgers University New Brunswick
依托单位国家：
美国
项目类别：
Standard Grant
财政年份：
2022
资助国家：
美国
起止时间：
2022-03-01 至 2025-02-28
项目状态：
未结题

来源：
https://www.nsf.gov/awardsearch/showAward?AWD_ID=2148375&HistoricalAwards=false
关键词：
Collaborative Research Lagrangian transport patchiness

项目摘要

Understanding processes that transport material in estuarine systems is central to fundamental studies of estuarine physics as well as to management practices in these socioeconomically important and highly anthropogenically impacted systems. Buoyant material, such as floating debris, marine organisms, oil and microplastics may be aggregated and trapped within estuaries or dispersed and discharged to the coastal ocean by these transport processes. Strong convergent surface flows across the estuary organize buoyant material into laterally narrow near-surface patches that may extend up to a few kilometers along the estuary. Local currents that move these patches may substantially differ from tidally and laterally averaged currents, which are often used to estimate estuarine transport characteristics. A major objective of this project is to contrast the transport of material in a frame work that follows the flow, known as the Lagrangian framework, with one based on a fixed point reference frame, or the Eulerian framework. Often the Lagrangian trajectories of material differ from those inferred from the Eulerian mean flows. The classic example stems from surface waves where the average velocity at a point (Eulerian) will be zero but a particle oscillating with the wave included flow will have an average velocity in the direction of wave propagation, due to the Stokes drift or Stokes velocity. This project will investigate the importance of Stokes transport in estuaries. The project research hypotheses are: (1) Stokes transport associated with amplitude and phase structure of tidal flows contribute significantly to the transport of buoyant material in both the along-channel and cross- channel directions. (2) Buoyant material organizes in surface patches due to the lateral estuarine circulations. (3) Patches of buoyant material are fundamentally transported by spatiotemporally localized currents that vary substantially across the estuary. (4) The observed spatiotemporal distributions of marine debris in Delaware Bay are a characteristic signature of Lagrangian estuarine transport. The project will use both modeling and observations to address transport of buoyant material in estuaries. This research will help solve practical real world problems related to marine pollution, gas exchange and fisheries. The PIs have close working relationships with resource managers and policy makers with whom they will communicate relevant new understanding. The project will train graduate and undergraduate students, and both PIs and students will participate in public outreach events. This project will examine transport of buoyant material in estuaries, specifically the Delaware Estuary, including its aggregation within estuaries, and the effects of resulting patchiness of buoyant material on its transport through the estuary. The hypotheses will be addressed through an integrated research program that employs original concept models as well as observations and simulations. Research objectives include: (1) Assess and advance idealized linear and weakly-nonlinear models of the three-dimensional estuarine circulations to determine key factors that control secondary circulations, such as bathymetry, tides, Coriolis force, and baroclinicity. (2) Develop and evaluate a Lagrangian framework for the estuarine circulation based on the integration of the idealized models with existing field observations and an asymptotic Stokes drift analysis to contrast fundamental differences between the Eulerian and Lagrangian approaches. (3) Conduct and integrate hydrodynamic simulations and field observations of the Delaware Estuary to understand tidal neap-spring and high-low river discharge variability. (4) Apply the Lagrangian framework to simulation and observation results, as well as recent marine debris observations, to reveal principal Lagrangian transport characteristics and improved estuarine transport estimates. By exploring and developing a Lagrangian framework this project would fundamentally advance our understanding of the physics of estuarine transport processes. This work will transform the current paradigm of estuarine material transport to include new lateral transport processes, thereby advancing the current conceptual understanding of buoyant tracer dynamics in an estuary, and will contribute to solving practical real world problems.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.

了解河口系统中物质输送的过程对于河口物理的基础研究以及在这些具有重要社会经济意义和高度人类活动影响的系统中的管理实践是至关重要的。漂浮物质，如漂浮的碎片、海洋生物、石油和微塑料，可通过这些运输过程聚集并滞留在河口或分散并排放到沿海海洋。穿过河口的强烈汇聚的表层水流将浮力物质组织成横向狭窄的近地表斑块，这些斑块可能沿着河口延伸达几公里。移动这些斑块的本地流可能与潮汐和横向平均流有很大不同，后者通常被用来估计河口的输运特征。该项目的一个主要目标是将遵循流动的框架(称为拉格朗日框架)中的材料运输与基于定点参考框架或欧拉框架的框架中的材料运输进行对比。物质的拉格朗日轨迹通常不同于从欧拉平均流推断的轨迹。经典的例子源于面波，其中一点的平均速度(欧拉)将为零，但由于斯托克斯漂移或斯托克斯速度，与包含波的流动一起振荡的粒子将具有沿波传播方向的平均速度。本项目将调查河口斯托克斯运输的重要性。本项目的研究假设是：(1)与潮流的幅值和相位结构有关的斯托克斯输运对沿航道和跨航道方向的浮力物质的输运都有重要的贡献。(2)由于河口侧向环流，浮力物质以表面斑块的形式组织。(3)浮力物质的斑块基本上是由时空上局部的洋流输送的，这些洋流在整个河口变化很大。(4)特拉华湾海洋垃圾的时空分布是拉格朗日河口输运的特征。该项目将使用建模和观测来解决河口浮力物质的运输问题。这项研究将有助于解决与海洋污染、气体交换和渔业相关的现实世界实际问题。采购经理与资源经理和政策制定者有密切的工作关系，他们将与他们交流相关的新谅解。该项目将培训研究生和本科生，个人投资者和学生都将参加公共宣传活动。该项目将研究河口，特别是特拉华州河口的浮力物质的输送，包括它在河口内的聚集，以及由此产生的浮力物质的斑块对其通过河口的输送的影响。这些假说将通过采用原始概念模型以及观察和模拟的综合研究计划来解决。研究目标包括：(1)评估和发展河口三维环流的理想线性和弱非线性模式，以确定控制次生环流的关键因素，如水深、潮汐、科里奥利力和斜压性。(2)建立和评估河口环流的拉格朗日框架，其基础是将理想化模式与现有的野外观测和渐近的斯托克斯漂移分析相结合，以对比欧拉方法和拉格朗日方法之间的根本差异。(3)对特拉华州河口进行水动力模拟和现场观测，以了解潮汐小潮和河流流量的高低变化。(4)将拉格朗日框架应用于模拟和观测结果以及最近的海洋废弃物观测，以揭示主要的拉格朗日输运特征和改进的河口输运估计。通过探索和发展拉格朗日框架，该项目将从根本上促进我们对河口输运过程物理学的理解。这项工作将改变目前河口物质运输的范例，包括新的横向运输过程，从而促进目前对河口浮力示踪剂动力学的概念性理解，并将有助于解决现实世界中的实际问题。该奖项反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。