Collaborative Research: The Role of Coastal Fronts in Mixing and Ventilating Coastal Waters

海岸锋是上层海洋的区域，有清晰的边界，将不同的水团分开。锋面与增强的湍流和垂直速度有关。强分层、气流辐合和锋面附近增强的垂直通量之间的相互作用对世界海洋内的气体和能量交换具有重要和直接的影响。使用最先进的方法（包括仪器化的自主水下航行器（AUV）和漂流平台）进行详细观察，以解决导致沿海锋面附近混合和垂直交换增强的精细尺度动力学问题。收集的数据和随后的分析将改进对汇率的估计，汇率决定了系统对酸化和缺氧、初级生产和物质运输的敏感性。这项研究将提高我们预测和管理沿海海洋酸化和缺氧的能力，并为上层海洋交换过程提供新的研究线索。该项目还将有助于青年科学家事业的发展。外展活动包括参加一年一度的华盛顿大学探索日活动，该活动吸引了来自地区K-12学校的10,000多名学生参观校园并了解当前的研究。通过美国国家科学基金会REU项目寻求本科生研究机会，以及促进华盛顿大学和加州大学圣巴巴拉分校土木与环境工程系研究生和本科生的参与，将促进学生在多个层面的参与。研究的重点是海岸锋面附近的表面波破碎、气泡夹带和下流辐合之间的相互作用，主要目标是研究这些位置湍流交换的具体性质和短暂性。提出的工作建立在最近使用SWIFT漂移器和REMUS 600自主水下航行器测量上层海洋湍流耗散率的结果之上。紊流能量学和雷诺应力的详细测量将提供在偶发性和瞬态锋面特征交换过程的变革性观点。这将与通过控制体积分析和地形形式阻力估计驱动锋面形成的动力学联系起来。通过收集本文提出的综合原位测量数据，可以定量表征地表锋面在沿海和河口水域通风和混合中的作用。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

Coastal fronts are regions of the upper ocean with sharp boundaries that separate distinct water masses. Fronts are associated with conditions of enhanced turbulence and vertical velocities. Interactions between strong stratification, flow convergence, and enhanced vertical fluxes near fronts have important and immediate implications for gas and energy exchange within the world’s oceans. Detailed observations using state-of-the-art methods that include an instrumented autonomous underwater vehicle (AUV) and drifting platforms would be used to resolve fine scale dynamics that lead to the enhancement of mixing and vertical exchange in the vicinity of a coastal front. The data collected and subsequent analysis would improve estimates of exchange rates that determine a system’s susceptibility to acidification and hypoxia, primary production, and transport of material. This study will improve our ability to predict and manage coastal ocean acidification and hypoxia, as well as enable new lines of inquiry into upper ocean exchange processes. The project will also contribute to the development of the career of a young scientist. Outreach efforts include participation in the annual University of Washington Discovery Days event, which draws over 10,000 students from regional K-12 schools to visit the campus and learn about current research. Student participation at multiple levels would be fostered by pursuing undergraduate research opportunities through the NSF REU program as well as promote involvement of graduate and undergraduate students within the Department of Civil and Environmental Engineering at the University of Washington and UC Santa Barbara. The interaction between surface wave breaking, bubble-entrainment, and downwelling convergence in the vicinity of coastal fronts are the focus of the study, with the primary goal being to investigate the specific nature and transiency of turbulent exchange at these locations. The proposed work builds on recent results using SWIFT drifters as well as a REMUS 600 autonomous underwater vehicle to measure upper ocean turbulent dissipation rates. Detailed measurements of turbulent energetics and Reynolds stresses will provide a transformative view of exchange processes at episodic and transient frontal features. This would be linked to dynamics driving frontogenesis through control volume analyses and estimates of topographic form drag. Through the collection of comprehensive in-situ measurements proposed here, the role(s) of surface fronts in ventilating and mixing coastal and estuarine waters would be quantitatively characterized.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.