Water Mass Transformation and Downwelling around Islands

岛屿在动力学上很有趣，因为它们对岛屿大陆架和公海之间的交换构成强烈的动力学约束，并可能导致重要的水团转换和输出。这些动力也影响大陆架、斜坡和远离岛屿的环流。理想的和现实的数值海洋模型将与简单的解析模型相结合，以更好地了解是什么控制了岛屿周围的水团转化和净下潜。这里强调的理想化框架将使人们更清楚地了解为什么这些过程在不同岛屿之间不同，以及它们在不断变化的气候中可能会如何变化。这项资助的工作将用于伍兹霍尔海洋研究所的本科和研究生教育项目。分析模型和涡旋解析数值模型的结合将提供对动力学和热力学的见解，这些动力学和热力学控制着岛架上的湍质通量和混合以及产品水向周围海洋的出口。将特别关注不对称强迫情况，其中浮力强迫，风应力，周围海洋或底部地形在岛屿周长周围变化。一般方法将使用理论来识别相关的无量纲数字，并提供一个动态框架来指导和解释数值模型计算。数值模型将用于验证理论的基本预测，同时更完整地解决非线性涡旋通量和对流等重要过程。感兴趣的量包括：产品水质量的性质；上升流和下升流分布；净沉降质量通量；通过大陆架断裂的诱导环流和通量。

Islands are dynamically interesting because they pose strong dynamical constraints on the exchange between the island shelf and the open ocean, and can result in important water mass transformation and export. These dynamics also influence the circulation on the shelf, on the slope, and far from the island. Idealized and realistic numerical ocean models will be combined with simple analytic models to better understand what controls water mass transformation and net downwelling around islands. The idealized framework emphasized here will provide a clearer understanding of why these processes differ between different islands and how they might be expected to change in a changing climate. Work supported by this grant will contribute to both undergraduate and graduate education programs at the Woods Hole Oceanographic Institution.The combination of analytic models and eddy resolving numerical models will provide insights into the dynamics and thermodynamics that control the diapycnal mass flux and mixing on island shelves and export of product waters to the surrounding ocean. Particular focus will be given to asymmetrical forcing situations in which the buoyancy-forcing, wind stress, surrounding ocean, or bottom topography vary around the island perimeter. The general approach will use theory to identify the relevant non-dimensional numbers and provide a dynamical framework with which to guide and interpret the numerical model calculations. The numerical models will be used to test the basic predictions from the theory while more completely resolving important processes such as nonlinear eddy fluxes and convection. Quantities of interest include: properties of product water masses; distribution of upwelling and downwelling; net diapycnal mass flux; induced circulations and fluxes across the shelf break.