Wave-Driven Flows over Coral Reefs and their Effects on Lagoon-Ocean Exchange

将进行观测和模拟相结合的智能MERITA研究，以研究珊瑚礁上波浪驱动的流动的正压动力学以及伴随而来的海礁交换。这项工作旨在测试辐射应力理论如何很好地解释典型珊瑚礁/泻湖复合体的复杂地形上的流动，并研究从珊瑚礁中流出的射流如何与珊瑚礁上由波浪驱动的流入相互作用，从而确定净交换。现场观测将在莫雷亚的一个微型潮汐泻湖系统进行，在一系列波浪条件下进行。在每个实验中，声学多普勒海流剖面仪(ADCP)阵列和波浪/潮汐测量仪将沿跨礁断面部署，以解决跨礁动量平衡中的关键项，并获得迄今对珊瑚礁底部应力的最佳估计。将部署第二个阵列来测量通过泻湖和离开珊瑚礁通道的质量通量，以完成该系统的水和交换预算。最后，将使用密集的水柱和漂流物释放的船上剖面来确定PASS喷流的命运和重新卷积到珊瑚礁的可能性，特别是在存在持续沿岸流动的情况下。与现场程序并行，将进行一系列关于理想化的礁-泻湖-山口系统的数值试验，绘制动态平衡的参数空间。数值工作将使用斯坦福大学开发的开源环流模式(3D，斜压，非静力，非结构网格，有限体积，并行程序)与风浪模式耦合。拟议的模拟着眼于一类近岸流动，与海滩上的类似流动相比，这类流动受到的关注较少，应该会揭示目前波浪和平均流动相互作用的模型在多大程度上适用于与海滩不同的几何形状。模型和观测的“对峙”可能会为使用新的波浪模型指明方向，甚至会突出目前还没有解释的理论和观测之间的根本区别。从浅水动力学的观点来看，波浪对小进水口外流的调节作用也是新颖的。更广泛的影响珊瑚礁的功能，一些最受威胁和最具经济价值的海洋生态系统，严重依赖于水动力学。这些实验和计算将显著提高我们对珊瑚礁水动力学的理解，从而加快建立预测模型的进程，这些模型可以用来制定环境政策，或者根据“连通性”的知识来设计海洋保护区。从跨学科的角度来看，这项研究将为从事珊瑚礁研究的生物学家和地球化学家提供了解远程强迫(膨胀)如何改变感兴趣的生物体或化学反应和转化的条件的手段。该研究团队有与其他学科接触和合作的记录。对该系统的物理了解将大大有助于LTER的众多活动(如浮游动物、鱼类生态、营养动态等)。在现场。数值环流模式将为未来对该系统和类似系统的任何3D物理生物学建模提供必要的基础。通过我们与其他用户共享模型源代码的长期做法，对斯坦福模型开发的投资将使海洋界受益。在教育方面，该项目将培训2名女性博士生(均为国家科学基金会研究员)，并指出女性在物理海洋学领域的比例偏低。他们都将学习观测物理海洋学、科学潜水和高性能计算。现场工作还将涉及其他几名研究生和本科生，他们将接触和参与跨学科实验，并获得复杂沿海水流研究的经验。

ABSTRACTOCE-0622967Intellectual meritA combined observational and modeling study will be conducted to address barotropic dynamics of wave-driven flows over coral reefs and the concomitant ocean-reef exchange. The work is designed to test how well radiation stress theory explains flows over and through the complex topography of typical reef/lagoon complexes, as well as examine how outflow jets from reef lagoons interact with the wave-driven inflow over a reef and thus determines net exchange. The field observations will be conducted at a micro-tidal lagoon system on Moorea, over a range of wave conditions. In each experiment, an array of Acoustic Doppler Current Profilers (ADCPs) and wave/tide gauges will be deployed along a cross-reef transect to resolve the key terms in the cross-reef momentum balance, and obtain the best estimates to date of bottom stress over coral reefs. A second array will be deployed to measure mass fluxes through the lagoon and out the reef pass, to complete a water and exchange budget for the system. Finally, intensive shipboard profiles of the water column and drifter releases will be used to determine the fate of the pass jet and potential for re-entrainment to the reef, particularly in the presence of persistent alongshore flow. In parallel with the field program, a series of numerical experiments on idealized reef-lagoon-pass systems will be conducted, mapping the parameter space of dynamical balances. The numerical work will use the open source circulation model developed at Stanford University (3D, baroclinic, non-hydrostatic, unstructured grid, finite volume, parallel code) coupled to a wind-wave model. The proposed simulations looks at a class of nearshore flows that has received less attention than has similar flows on beaches and should reveal the extent to which the present model of the interaction of waves and mean flows works for a geometry that is different than that of a beach. The "confrontation" of model and observation may point the way to using new classes of wave models, or even highlight fundamental differences between theory and observation that have no present explanation. From the standpoint of shallow water dynamics, the role of waves in modifying the outflow from a small inlet is also novel. Broader ImpactsThe functioning of coral reefs, some of the most threatened and economically valuable marine ecosystems, are strongly dependent on hydrodynamics. The experiments and computations will significantly improve our understanding of coral reef hydrodynamics, and thus speed progress toward predictive models that could be used to set environmental policies, or in designing marine reserves based on knowledge of "connectivity". From an interdisciplinary standpoint, this research will provide biologists and geochemists working on reefs with means of understanding how remote forcing (swell) changes conditions for organisms of interest or for chemical reactions and transformations. The research team has a record of engaging and collaborating with other disciplines. The physical understanding of the system will greatly aid numerous LTER activities (e.g. zooplankton, fish ecology, nutrient dynamics, etc.) at the field site. The numerical circulation model will provide the essential foundation any future 3D physical biological modeling of this and similar systems. Investment in the Stanford model development will benefit the oceanographic community via our long-standing practice of sharing model source code with other users. In terms of education, this project will involve the training of 2 women PhD students (both NSF fellows), noting that females are underrepresented in physical oceanography. They will both learn about observational physical oceanography, scientific diving and high performance computing. The field work will also involve several other graduate and undergraduate students who will be exposed to and participate in interdisciplinary experiments, as well gaining experience with studies of complex coastal flows.