Collaborative Research: Exchange and Dispersion Across the Inner Shelf: Understanding the Importance of Spatial Variability

这项研究试图了解大陆架内部100s到10s公里尺度上的流场的空间变异性，它对交换和扩散的贡献，以及它对沿海系统的影响。最近对马萨诸塞州玛莎葡萄园岛南部沿海海洋的观测记录了令人震惊的空间可变流动的例子，这些流动有可能推动集中的横向交换穿过大陆架，这与经常研究的沿大陆架对上升流或下升流的统一反应相媲美。然而，我们对这些尺度上的流场特征几乎一无所知，因为传统的观测技术和典型的现实陆架模型不能充分解决这些尺度上的问题。这很可能是第一次对沿海海洋从100米到10公里尺度上的海流变异性进行全面研究，方法是采用高分辨率高频雷达表面流、对地下速度和水文地质的密集观测、质量漂移释放以及与现实和理想化的数值模式的比较。这项拟议的工作将量化穿过大陆架的水团的总通量，风、层结和水深测量中的空间变异性对交换的相对重要性，以及空间可变弥散的作用。以前量化沿海海洋交换率的努力通常集中在由于沿陆架均匀的风驱动的动力学而导致的输送。虽然在大多数沿海地区发现了由于主要海角或海角、水深不规则或风场不均匀而造成额外输送的证据，但这些可变性来源对整个大陆架交换和扩散的相对影响尚未量化。此外，小尺度和/或瞬变特征的影响一直没有得到解决，这些特征可能是空间相关的交换或弥散的重要来源。这种对玛莎葡萄园岛以南沿海海洋交换的全面看法，包括使用拉格朗日轨迹分析以及基于欧拉的交通研究，将能够捕捉到更广泛的空间变异性，并将量化瞬变事件的发生、驱动因素及其对沿海系统的重要性。水团从毗邻海岸的浅水移动到离岸更大的沿海海洋，控制着近岸和全球海洋之间的热量、盐分、营养物质和污染物的流动。通过全面审视跨陆架运输，这项工作的结果将记录空间变异性对沿海系统的潜在影响。这一努力将提高我们量化和预测交换的能力，这些交换对于评估沿海地区的生产力至关重要，以及对监测有害藻华、污染物和搜救行动的命运至关重要的分散率。私人投资机构积极参与世界卫生组织和马萨诸塞州大学达特茅斯分校的教学和指导工作，并与沿海管理人员和规划者进行互动。与NOAA东北水产科学中心合作，一项广泛的教育计划将通过额外的漂流部署，将该地区的K-12学生引入正在进行的科学研究

This study seeks to understand spatial variability in the flow field over the inner part of the continental shelf at scales of 100s of meters to 10s of kilometers, its contribution to exchange and dispersion, and its implications for coastal systems. Recent observations of the coastal ocean south of Martha's Vineyard, MA have documented startling examples of spatially-variable flows with the potential to drive focused lateral exchange across the shelf rivaling that due to the frequently-examined along-shelf uniform response to upwelling or downwelling. Yet, we know almost nothing about the characteristics of the flow field at these scales because conventional observational techniques and typical realistic shelf models do not adequately resolve these scales. This will likely be the first comprehensive study of current variability in the coastal ocean at scales from 100s of meters to 10s of kilometers by employing a unique combination of high-resolution HF radar surface currents, dense observations of subsurface velocity and hydrography, and mass drifter releases along with comparisons to realistic and idealized numerical models. The proposed work will quantify the total flux of water masses across the shelf, the relative importance of spatial variability in the wind, stratification, and bathymetry on exchange, and the role of spatially-variable dispersion.Previous efforts to quantify the rates of exchange in the coastal ocean have generally focused on the transport due to along-shelf uniform, wind-driven dynamics. While evidence of additional transport due to major capes or headlands, bathymetric irregularities, or non-uniform wind fields has been found in most coastal areas, the relative impact of these sources of variability on exchange and dispersion across the shelf have not been quantified. Additionally, the effects of small-scale and/or transient features, potentially important sources of spatially-dependent exchange or dispersion, have never been resolved. This comprehensive view of exchange across the coastal ocean south of Martha's Vineyard, including the use of Lagrangian trajectory analyses in addition to the Eulerian-based transport studies, will enable a much broader range of spatial variability to be captured and will quantify the occurrence of transient events, their drivers, and their importance for coastal systems.The movement of water masses from the shallow waters adjacent to the coast to the larger coastal ocean offshore controls the flux of heat, salt, nutrients, and pollutants between the nearshore and the global ocean. By providing a holistic look at across-shelf transport, the results of this work will document the potential effects of spatial variability on coastal systems. This effort will improve our ability to quantify and predict the exchange critical to assessing the productivity of coastal areas and the dispersion rates critical to monitoring the fate of harmful algal blooms, pollutants, and search and rescue operations. The PIs are actively involved in teaching and mentoring at WHOI and UMASS Dartmouth as well as interacting with coastal managers and planners. In collaboration with the NOAA's Northeast Fisheries Science Center, a broad educational program will entrain K-12 students in the region into the science being conducted through additional drifter deployments