Intensification and impact of wave-breaking in river plumes

锋面形成障碍，限制了海洋中不同水团之间的营养物质和有机体的交换。这项研究将调查波浪破碎是否会加剧不断扩大的淡水河流羽流与近海周围咸水之间的锋面混合。这项工作还将有助于对波浪破碎和近地表湍流的总体理解，这些都影响着海洋中的无数过程。该项目将支持一名研究生和几项推广工作，包括维护一个研究博客和制作一个视频片段，该视频片段将由应用物理实验室/华盛顿大学网站主办。该项目将使用一个新的波浪-湍流测量平台来量化波浪能量通过河流羽流锋面和内部时的转化，以及波浪破碎湍流对羽流动力学和混合的影响。最重要的假设是，在波浪尺度与垂直羽流尺度相匹配的系统中，羽流速度梯度可以加强波浪破碎，将波能转化为湍流，并显著增加羽流混合。计划通过利用新的和现有的现场数据实现以下三个具体目标来验证这一假设：1)量化在锋面和河流羽流中的破裂造成的波能损失，2)量化在波浪破裂过程中近地表湍流的产生和这种湍流的垂直结构，以及3)评估波浪破裂湍流对河流羽流混合的影响。在一系列波浪条件下，将在中等尺寸的弗雷泽河羽流(加拿大不列颠哥伦比亚省)和较小尺寸的埃尔华河羽流(美国华盛顿州)中进行波浪、近地表湍流和浮力通量的测量。这些测量的结果将与来自更大的哥伦比亚河羽流的现有波浪和湍流数据进行比较，以确定不同系统中的锋面强度如何影响波浪-湍流动力学。这一过程对混合的影响将通过基于漂流者的盐分预算以及对弗雷泽河羽流中十多年渡轮横断面数据的分析来评估

Fronts form barriers that limit the exchange of nutrients and organisms between different water masses in the ocean. This study will investigate if wave breaking can intensify mixing at fronts between an expanding fresh water river plume and the ambient salt water offshore. The work will also contribute to the general understanding of wave-breaking and near-surface turbulence, which influence a myriad processes in the ocean. The project will support one graduate student and several outreach efforts which include maintaining a research blog and producing a video segment which will be hosted by the Applied Physics Laboratory/University of Washington website.This project will use a novel wave-turbulence measurement platform to quantify the transformation of wave energy as it passes through a river plume front and interior, as well as the impact of wave-breaking turbulence on the dynamics and mixing of the plume. The overarching hypothesis is that plume velocity gradients can intensify wave breaking, converting wave energy to turbulence, and significantly increasing plume mixing in systems where the wave scales match the vertical plume scale. The plan is to test this hypothesis by pursuing the following three specific objectives using new and existing field data: 1) quantify the loss of wave energy via breaking at fronts and within river plumes, 2) quantify the generation of near-surface turbulence during wave breaking and the vertical structure of this turbulence, and 3) assess the impact of wave breaking turbulence on mixing in river plumes. Measurements of waves, near-surface turbulence, and buoyancy flux will be done in the moderate-sized Fraser River plume (British Columbia, Canada) and the smaller-sized Elwha River plume (Washington, USA) under a range of wave conditions. Results from these measurements will be compared with existing wave and turbulence data from the much larger Columbia River plume to determine how wave-turbulence dynamics are influenced by frontal strength in different systems. The impact of this process on mixing will be assessed using drifter-based salt budgets as well as analysis of more than a decade of ferry transect data through the Fraser River plume